Explanation:
All animals are in one kingdom (called Kingdom Animalia); all plants are in another (Kingdom Plantae). ... Other systems have six or more kingdoms. Species are the smallest groups. A species consists of all the animals of the same type, who are able to breed and produce young of the same kind.
Years would be the independent variable because any sort of time is usually the independent variable.
I believe the correct answer is B)
I am Guessing Sperm and egg
