I think sister groups. Imagine them having the same parents.
C, when mutations are not always predictable they are random
Answer: mitosis.
During DNA replication a pair of chromosomes of from one cell genders two duplicated chromosomes (so the number of chromosomes is duplicated), then in the mitosis process the cell split into two identical cells each with half of the duplicated chromosomes, so at the end one cell with two chromosomes form two cells each with two chromosomes. So, the new generation of cells has the same number of chromosomes.
The answer is epididymis.
Epididymis is a tightly coiled mass of thin tubes that carries sperm from the testes to the ductus deferens in the ale reproductive system. Sperms matures as they pass through the epididymis so that they are ready to fertilize ova by the time they enter the ductus deferens. During the ejaculation stage of emission sperms are moved from the testes and the epididymis, where they are stored, to the beginning of urethra.
