Answer:
C
Explanation: C, because the graph shows that, beginning in the 1980s, the wingspans of living cliff swallows has decreased. Over the same period, the wingspans of cliff swallows found as roadkill has increased. This indicates that natural selection is acting against the phenotype of longer wingspans, resulting in a population with shorter average wingspan. In other words, alleles for shorter wings increase fitness, causing a change in the population’s gene pool.