Gregor Mendel Put Forth the Basic Principles of Inheritance, Publishing

Gregor Mendel put forth the basic principles of inheritance, publishing his findings in 1866. The significance of his work did not become widely known until 1900.
-Which of the following factors did not contribute to Mendel's success in his study of heredity?

A) His use of the pea plant
B) His study of plant chromosomes
C) His adoption of an experimental approach
D) His use of mathematics