Which sentence uses commas correctly? a. some rain has acid in it and this, can be dangerous. b. this " acid rain "can kill trees ,and ,it can also poison fish. c. take a belly flop in the pool, and you'll find that the water feels pretty hard. d. water itself is pure but ,it may carrry poisons in it.

At the edge of the lawn, behind the building, there was a line of underbrush and trees sloping down a hillside. beyond that, there was a playground next to a day-care center. they could hear shouts of children in the air, and when they looked through the underbrush, they could see bundled-up four-year-olds swinging on swings and racing around a playhouse. the operation would be carried out near children. –the hot zone, richard preston what is the author’s purpose for including this paragraph? check all that apply. to express his thoughts clearly to inform readers about the location to persuade readers to become scientists to entertain readers by showing how dramatic the situation is to encourage readers to protect children