In the scenario described, where female reindeer are giving birth to larger offspring over generations, the type of selection occurring is directional selection. This is because the population is favoring a trait (larger offspring) that pushes the average size to the right on the distribution curve.
As a result, the distribution curve for this trait would shift to the right over time, indicating that the average size of the offspring is increasing.
So the correct response is:
directional selection; the curve would shift to the right.