Q4: Which of these human activities is most likely to cause the excessive
growth of phytoplankton in the world's oceans? *

A. The use of chemical fertilizers that are carried by runoff into rivers.

B. The logging of old-growth forests, which results in erosion.

C. The spraying of chemical herbicides that reduce carbon dioxide in the air.

D. The mining of fossil fuels, which requires digging underground tunnels