<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:An investigator is studying the mechanism of HIV infection in cells obtained from a human donor. The effect of a drug that impairs viral fusion and entry is being evaluated. This drug acts on a protein that is cleaved off of a larger glycosylated protein in the endoplasmic reticulum of the host cell. The protein that is affected by the drug is most likely encoded by which of the following genes?? A: rev, B: gag, C: pol, D: env, E: tat,  <response>: This question is asking about the mechanism of action of a drug that impairs HIV fusion and entry into host cells. The drug acts on a protein that is cleaved off a larger glycosylated protein in the endoplasmic reticulum. This description indicates that the drug is likely targeting the HIV envelope Env protein, which is initially synthesized as a precursor protein gp160 and then cleaved by cellular proteases into gp120 and gp41 subunits. Gp120 and gp41 play key roles in HIV binding and fusion to host cells. The Env protein is encoded by the env gene. Therefore, the gene affected by this drug is most likely env.D: env 