As a Young Biologist, Charles Darwin Had Expected the Living

As a young biologist, Charles Darwin had expected the living plants of temperate South America would resemble those of temperate Europe, but he was surprised to find that they more closely resembled the plants of tropical South America. The biological explanation for this observation is most properly associated with the field of

A) meteorology.
B) embryology.
C) vertebrate anatomy.
D) bioengineering.
E) biogeography.