It Is Difficult to Imagine How Only Part of an Adaptation

Multiple Choice

It is difficult to imagine how only part of an adaptation could function, but Darwin explained this. How would he answer the question, "What good is 5% of an eye?"

A) Once an organism has the first 5% of an adaptation, the rest will quickly evolve.
B) Five percent of an eye is always better than a full eye since it is easier to grow. The difficulty is in explaining fully formed eyes.
C) Since variation is random, we don't expect to see more than about 5% of an eye in any species.
D) Five percent of an eye, perhaps a simple light-sensitive spot, is often better than having no eye at all.