6. When first proposed, Darwin's theory of natural selection did not fully explain how
evolution occurred. This was due to
A. Darwin's failure to recognize the tendency of organisms to over-
reproduce
B. Darwin's initial overemphasis of the significance of genetic drift
C. the fact that accurate mechanisms explaining genetic inheritance
were not widely known
D. the absence of accurate descriptions of the embryological
development of most plants and animals
E the absence of biochemical techniques to determine the genetic
similarities between species​