Recessive mutations are not lost from a gene pool, this is known as

(p + q)2 = $p^2$ + 2pq + $q^2$ = 1. Here, "p" is the frequency of dominant allele, $p^2$ is frequency of homozygous dominants, q is frequency of recessive allele and $q^2$ is frequency of homozygous recessive individuals. Darwin proposed that random mutations arise that changes characteristics of a population through the process of natural selection; he did not talk about dominant or recessive forms of mutations. Recessive mutations are accumulated within population in heterozygotes and are expressed when presented in homozygous conditions. The question is about recessive mutations. Thus, the correct answer is option C.