(1) Salt marshes absorb storm surge before it reaches houses. (2) Their roots lock carbon into deep mud. (3) Towns that paved their marshes now pay for sea walls. Which statement best expresses the central idea?

(1) Cities are replacing streetlights with dimmer, warmer lamps. (2) Bright white light scatters upward and hides the stars. (3) The warmer lamps also stop moths from swarming, so bats hunt normally again. How does paragraph 3 develop the central idea?

(1) Most wild bees nest in bare soil, not in hives. (2) Tidy lawns and heavy mulch seal that soil shut. (3) Gardeners who leave one sunny bare patch count more bees by the second summer. Which is the best objective summary?

(1) Ships once released ballast water carrying foreign snails into new harbors. (2) Ports now require the tanks be flushed far out at sea. (3) Since that rule, new arrivals have slowed. Which statement best expresses the central idea?

(1) One school moved lunch to the period after recess. (2) Students arrived hungry instead of rushing outside. (3) Kitchen staff weighed the trash and found a third less food thrown away. How does paragraph 3 develop the passage?

(1) Sea otters eat sea urchins. (2) Where otters disappeared, urchins stripped the kelp forests bare. (3) Kelp grew back within a few years of the otters' return. Which statement best expresses the central idea?

(1) Roman roads were built with a curved, crowned surface. (2) Rain ran off the sides instead of pooling in the stone. (3) Some stretches still carry traffic two thousand years later. Which is the best objective summary?

(1) Some libraries have begun lending tools. (2) A person who needs a drill twice a decade can simply borrow one. (3) Shelves that once held videos now hold saws and ladders. Which statement best expresses the central idea?

(1) Volcanic ash breaks down into unusually rich soil. (2) Farmers crowd onto the slopes of active volcanoes. (3) Evacuations there are slower because so many people live close. Which statement is too narrow to be the central idea?

(1) A town banned left turns at its busiest crossing. (2) Drivers complained about the longer routes home. (3) Crashes at that crossing fell by half within a year. How does paragraph 2 develop the passage?

(1) Peat bogs store carbon in waterlogged plant matter. (2) Drained bogs release that carbon as the peat dries out. (3) Crews are now blocking old ditches to flood the ground again. Which is the best objective summary?

(1) Night nurses at one hospital once rotated shifts weekly. (2) The hospital fixed each nurse to a steady schedule instead. (3) Sick days dropped and fewer nurses quit that year. Which statement best expresses the central idea?

(1) Hundreds of millions of birds die each year striking windows in the United States. (2) Glass mirrors the open sky. (3) Dots spaced a few inches apart across the pane cut strikes sharply. What does paragraph 1 contribute?

(1) A city hung shade sails over three bus stops. (2) Riders there waited about four minutes longer before giving up and walking. (3) Ridership at those stops rose that summer. Which is the best objective summary?

(1) Crews once put out every forest fire as fast as they could. (2) Dead wood piled deeper on the ground each decade. (3) When fire finally came, it burned hot enough to scorch the soil. Which statement best expresses the central idea?

(1) A bakery switched from plastic bags to paper ones. (2) Loaves began going stale a day sooner. (3) The owner started selling half loaves so less bread was wasted. How does paragraph 3 develop the idea?

(1) Coral bleaches when the water around it stays too warm. (2) Some reefs beside cool upwellings keep their color. (3) Crews now use those reefs to choose planting sites. Which statement is a supporting detail, not the central idea?

(1) A museum let visitors handle replicas of its objects. (2) Guides reported longer visits and more questions. (3) The originals stayed behind glass, untouched. Which is the best objective summary?

(1) Rice paddies kept flooded all season give off methane. (2) Farmers who drain the field once midseason cut those emissions. (3) Harvests in the trial fields held steady. Which statement best expresses the central idea?

(1) Streetcars once ran down the avenue. (2) The rails were paved over in the 1950s. (3) Crews digging for pipes still strike them, and each strike costs weeks. How does paragraph 3 develop the central idea?