If fertilization occurs when sperm swim inside a single egg embedded in the prothallus, then what happens inside the single egg embedded inside the prothallus?

Answer choices:
- Earth revolving around the sun
 - The area was once underwater
 - gastropod shells
 - it keeps an organism warm
 - remains of prehistoric life
 - fertilization occurs
 - allow growth
 - It helps them survive

 

      fertilization occurs    