Although the animals exhibiting external fertilization produce a large number of gametes, the chances of fertilization of these gametes are quite low. This is because they are subjected to movements of water, air, rain and also can be destroyed or eaten up by other animals. Therefore a large number of gametes are produced to ensure fertilization of at least some of them.

The size of animals or availability of food is not related to the production of gametes. Water does not promote the production of a large number of gametes. Thus, these statements are not the correct option.