Which of the following is an example of parasitism?

A. Clownfish defending sea anemone from other predators

B. Hookworms consuming blood from inside an animal's intestine

C. Barnacles living harmlessly on the side of a whale while collecting food

D. Tree frogs using the trees to hide from predators

The answer is B. Hookworms consuming blood from inside an animal's intestine.

Parasitism is a type of relation between species where a parasite benefits at the expense of the host. In this example, hookworms benefit at the expense of the host. They consume blood from inside an animal's intestine and can harm the host. Therefore, this is the example of parasitism.