Which of the following statements about change in ecosystems is true? a. ecosystems experience change through human activity only. b. ecosystems experience change through natural events only. c. ecosystems experience no change. d. ecosystems experience change through human activity and natural events.

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's

the most common type of reef is the fringing reef. this type of reef grows seaward directly from the shore. they form borders along the shoreline and surrounding islands.