Answer:
C). Increasing sickle-cell allele frequency.
Explanation:
Homozygotes are defined as the person who possesses two similar alleles(genes acquired from both the parents) that leads them to have a particular trait in them. While heterozygotes are illustrated as the individual having two distinct genes or alleles that leads them to possess varying traits.
As per the question, the net influence of this subjection in Malaria endemic areas is by 'increasing sickle-cell allele frequency' as it would assist in providing resistance against such diseases. Sickle-cell trait aids to offer a shielding benefit against the diseases like Malaria. Thus, option C is the correct answer.