You are presented with the question "what requires penetration?" and the following answer choices: 
- gravity
 - weathering
 - gastropod shells
 - the skin
 - an object
 - death
 - Veins and arteries.
 - fertilization

Now knowing that fertilization occurs when a sperm and an egg fuse to form a diploid zygote and penetration is when the sperm and egg meet and the sperm makes it way into the egg cytoplasm, choose the best answer.


 

        fertilization 