Choose the correct word/phrase to complete the sentence.
Most animals in the zoos ______ in captivity.

In the given sentence "Most animals in the zoos are bred in captivity," the correct word/phrase to complete the sentence is are bred.
The verb "are bred" is in the present tense and passive voice. It correctly describes the action of animals being raised or reproduced in captivity, which is the context of the sentence.
Let's examine the other options:
A. "have breed" is incorrect because it does not form a grammatically correct structure. The correct form would be "have bred" for plural animals.
B. "are being breeding" is incorrect as it uses a wrong form of the verb "being breeding." The present continuous tense is not suitable in this context.
D. "breeds" is incorrect as it is in the present tense and does not match the sentence structure. The correct verb form for this sentence should be in the present passive voice, "are bred."
Therefore, the correct answer is "are bred" (Option C).