If timing is critical when a sperm and an egg fuse, then when is timing critical?

Answer choices:
- a hemisphere is tilted away from the sun
 - object is kicked
 - movement of tectonic plates
 - flow of electrons
 - when the sperm and egg fuse
 - Earth revolving around the sun
 - Warm air moving into cold air
 - seed dispersal

 

     when the sperm and egg fuse     