C - Microevolution
Work Step by Step
The finches population's genetic composition changed due to the environmental change of seed size availability. The larger seeds were more prevalent at first, which allowed the bigger-beaked birds to have a higher fitness, but later, smaller seeds became more common and thus, the smaller-beaked birds had a higher fitness. This change in genetic material, however, did not ultimately lead to speciation, which means that this is microevolution (a change in genetic composition within a species).