Put an h next to the items that describe human systems put a p next to the items that describe physical systems. canals faults floods bridges

Human Systems  --  canals , bridges

Physical Systems  --  faults , floods

Explanation:

Certain geography terms like the canals an bridges are related to the human systems and the faults and the floods are related to the physical environmental systems that are natural systems. Human aspects includes the man-made world.

Answer (d) the greenhouse effect is primarily caused by car and trucks;