The answer is A.
If the bicipe muscle contracts it will bring the forearm up because the insertion of this muscle is in the forearm.
One of the functions of this muscle is flexing the elbow, which would result in the action i already mentioned.
It couldn't be B, because that would be the work of another muscle, the triceps.
The units of evolution are populations and not individuals because a variation or a mutation in an individual is not sure to last or produce offsprings having the same variation or mutation. The proof that a species has truly evolved is when the variation has allowed the species to survive its environment and produce generations carrying the same variation.
Your answer would be Interphase
