Answer the following question given this paragraph: 

Unlike sponge adults, sponge larvae can swim. They have cilia that propel them through the water. As larvae develop and grow, they become more similar to an adult sponge and lose their ability to swim.


Q: What helps to propel sponge larvae through the water?

 Choices:

- mucus

- antennae

- tentacles

- cilia

A:
cilia
