Select the odd one out.

What is the $Antrum$?

What happens upon the fertilization of the egg nucleus with the sperm nucleus?

Do all the gametes formed from a parent organism have the same genetic composition (identical $DNA$ copies of the parental genome)? Analyse the situation with the background of gametogenesis and provide a suitable explanation.

The difference between $Spermiogenesis$ and $Spermiation$ is:

For normal fertility in males,what percentage of sperms must have normal shape and size,and what percentage of sperms must show vigorous motility?