The Exquisite Complexity of Traits Such as the Vertebrate Eye

Multiple Choice

The exquisite complexity of traits such as the vertebrate eye seems to pose a problem for evolution by natural selection. How do evolutionary biologists think that complex eyes evolved?

A) Complex eyes arose multiple times independently by a single mutation.
B) Intermediate forms of eyes were functional and selected for in the past but were selected for a function other than vision.
C) Eyes evolved in gradual steps, each of which was fully functional and adaptive in improving visual acuity.
D) Precursors to complex eyes were not adaptive and therefore were not subject to evolution by natural selection.