English morphological rules detail how words relate to other words. Thus, my best assumption would be because BOLDEST is an adjective whereas BOLDLY is an adverb.
Answer:
d
Explanation:
she is riding a bike and not using gas that is harming the earth
Answer:
Caetano was one of the greatest musicians, behind Sam Cooke of course.
Explanation:
Gave up their life for a cause.