The correct option is
B are bred
Option A: The auxiliary, 'have' is used to form the perfect tense. Eg: 'have bred' (present perfect tense) and 'have been breeding' (present perfect continuous tense). It is also used along with 'to+ present tense form of the verb' to indicate an obligation. Eg: 'have to breed'. However, 'have+ present tense form of the verb' (have breed) is grammatically incorrect and does not convey any meaning. Hence, option A is incorrect.
Option B: The verb form, 'are+being+past tense form of the verb' (are being bred) can be used to form the indicative present continuous tense. However, the verb form, 'are being breed' is grammatically incorrect. Hence, option B is incorrect.
Option C: The verb form, 'are bred' is in indicative present tense. It indicates as a fact, how the animals in captivity are maintained. As this is grammatically correct, option C is correct.
Option D: The verb, 'breeds' is in simple present tense form. The subject, 'Most animals' is in the third person and plural form. Along with this subject, the verb in present tense is used without the letter 's'. Hence, 'Most animals breed' is correct. 'Most animals breeds' as given in option D is grammatically incorrect. Hence, option D is incorrect.