Because you cannot test it or observe it.
A scientific theory are created through the scientific method, in the scientific method you need to be able observe it and experiment.
Explanation:
Red and yellow bell........... - genetic diversity
A park has....... - species diversity
Five different bird..... - species diversity.
The answer is Monosaccharide
In humans sperms can survive 3 -5 days within the female reproductive tract.
The ideal time of fertilization is around ovulation when the egg is in the fallopian tube. After travelling through the vaginal canal, the strongest sperm make it to the cervix. From here, the sperm must travel through the uterus and into one of the fallopian tubes.