What Led Darwin to Change His Beliefs About Fixity of Species

Multiple Choice

What led Darwin to change his beliefs about fixity of species?

A) renewed interest in the biblical account of creation
B) observation of language variation in human populations in the British Isles
C) observations of no documentable difference in plant and animal population over wide geographic areas
D) observations that distinct but closely related groups of plants and animals inhabited isolated islands
E) none of these