The correct option is A motile gametes
Zoospores are naked motile spores. They are asexual reproductive units which are capable of growing independently. They are formed in lower plants like algae and few fungi. They germinate with the onset of favourable conditions.
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves.
So the correct answer is "motile gametes".