How do biotechnologies such as hybridization and the introduction of mutations increase genetic variation? short answers

The afrikaners are an example of a founder effect that occurs when a new colony is started by a few members of the original population and the random decrease in genetic variation is an example of

What is the term for the two sets of chromatids formed in the parent cell a.haploid b.diploid c.gamete d.tetrad

Idon’t know the answer and i’ve been stuck on it for a while now skskskskks