According to the Text, the Major Principle of Darwin's Theory

According to the text, the major principle of Darwin's theory is reproductive fitness, which refers to

A) the unlikelihood that an individual will become a parent and grandparent.
B) the likelihood that same-sex siblings will never be reproduced.
C) the likelihood that an individual will become a parent and grandparent.
D) the chance that mates will eventually find themselves a fit for each other.