Because evolution is a theory, that means:
a. it is a guess or a hunch.
b. it has very little evidence to support it.
c. scientists may or may not believe in it.
d. it has never been observed.
e. none of the above

The correct answer will be option-E.

Explanation:

A scientific theory is a well-substantiated idea which explains any natural phenomenon or event of nature in depth. A theory is the elaborate form of the hypothesis.

A scientific hypothesis gets transformed into a theory when it is supported by the evidence from many earlier experiments as well as the repeated experiments like fossils in the evolution.

Since, a theory is not based on the guess, belief and opinions and is based on the evidence which supports the evidences, therefore, option-E is the correct answer.