The situation described involves female reindeer in a Finnish population giving birth to larger offspring over generations, which indicates a shift towards larger size. This is indicative of directional selection, where one extreme phenotype (in this case, larger size) becomes more advantageous and increases in frequency within the population.
As a result, the distribution curve for this trait would change over time by shifting to the right, indicating that larger offspring are being favored.
Therefore, the correct response is: directional selection; the curve would shift to the right.