Before the 1940s, Scientists Believed That Proteins, Rather Than DNA

Before the 1940s, scientists believed that proteins, rather than DNA, were the carriers of genetic material in the cell. Why?

A) Proteins are present within the nucleus.
B) Proteins are abundant within the cell.
C) Twenty different amino acids could produce a large number of unique combinations.
D) Proteins are able to self replicate.
E) Proteins are routinely exported from the cell.