Which interaction best illustrates the concept of mutualism?
a) jaguars feeding on wild pigs.
b) squirrels playing with other squirrels.
c) malaria protozoans living on the blood of a host.
d) nitrogen-fixing bacteria in root nodules of legumes.

Which sentences describes a cycle of dependency? a. aid harms the local economy creating the need for more aid.b. aid improves infrastructure and creates more wealth and more good infrastructure.c. aid programs become more reliable over time so people can depend on them.d. no answer is correct