Answer: Mutation. The allelic variations that make evolution possible are generated by the process of mutation, but new mutations change gene frequencies very slowly, because mutation rates are low. Assume that the gene allele A1 mutates to allele A2 at a rate m per generation and that at a given time the frequency of A1 is p.
Explanation:
Teh second statement, they can harm you but some strains are beneficial
The portion of the Moon's surface that cannot be directly observed from Earth
