Answer the following question given this paragraph: 

Sperm are released into the surrounding water through the osculum. If they enter a female sponge through a pore, they may be trapped by collar cells. Trapped sperm are delivered to eggs inside the female body, where fertilization takes place. The resulting zygote develops into a larva. Unlike the adult, the larva is motile. It is covered with cilia that propel it through the water. As the larva grows, it becomes more similar to an adult sponge and loses its ability to swim.


Q: Unlike an adult sponge, what stage is motile due to cilia that propel it through water?

 Choices:

- parasite

- zygote

- pupa

- larva

A:
larva
