Suppose scientists determine that a set of genes is significantly more prevalent in murderers than in the population at large. Would that mean that murderers are not at fault for what they do? Why or why not?

No

Explanation:

That a gene is common to all murderers in the population does not mean that murderers are not at fault for their crimes.

Having a gene that correlates with murder just gives one a genetic tendency but the environment and personal choice still have to influence the decision to commit the crime. In other words, one might have the genetic tendency to commit murder but still has to be environmentally enabled and the ability to choose to either do it or otherwise. Nature, nurture, and personal choice would have to synergistically work together for the phenotypic expression of such a gene.

i believe your answer would be c.. : )