Use the Following Graph and Information to Answer the Question

Multiple Choice

Use the following graph and information to answer the question.
Flycatcher birds that migrate from Africa to Europe feed their chicks a diet that is almost exclusively moth caterpillars. The graph shows the peak dates of flycatcher arrival in Europe, bird hatching, and peak caterpillar season for the years 1980 and 2000. The y-axis is a measure of the abundance of birds, hatching chicks, and caterpillars.

The shift in the peak of caterpillar season is most likely due to ________.

A) earlier migration returns of flycatchers
B) an innate change in the biological clock of the caterpillars
C) global warming
D) acid precipitation in Europe