Why didn't Mendel find linkage?

Options

A. Some genes were linked, but they were too close together to cross over.
B. All seven genes were on separate chromosomes.
C. Mendel did detect linkage. He discovered this genetic phenomenon.
D. Some genes were linked, but they were too far apart for crossing over to be distinguished from independent assortment, or linked genes were never tested for at the same time in the same cross.

Answer

D