The correct option is A.
Proactive interference refers to the tendency of the knowledge that one had learned previously to prevent one from subsequent learning. Thus, proactive interference is the difficulty that comes with learning new things due to the stuffs that one had learned before. For instance, an individual may find it difficult to learn Spanish because he has previously learn German.<span />
1 is C - see first attachment. Genotypes with Y's represent males, and big R represents red eyes, while little r represents white eyes. For example XRxr is a heterozygous (red-eyed) female, and XrYr is a homozygous white-eyed male.
2 is B because the absence of functional proteins and some ribosomes due to the mRNA strand is not as detrimental as the loss of the entire cell.
3 is B. (The insertion of 3 base pairs into a genetic sequence is the length of a single codon, meaning that only one amino acid in the entire polypeptide was added)