Fact 1: Gametes then unite in fertilization and form a diploid zygote.

Fact 2: Sperm and eggs are cells known as gametes.

Given the two facts above, answer the question "What is formed when a sperm and egg unite in fertilization?" with the following options: 
- a haploid
 - two sperms
 - rapid expansion
 - gastropod shells
 - Chemical energy
 - peachleaf willow
 - an infant human
 - a diploid zygote


 

        a diploid zygote 