All of the Following Pea Plant Feature Were Favorable to the Success

Multiple Choice

All of the following pea plant feature were favorable to the success of Mendel's experiments,except  

A) true-breeding varieties were available.
B) the plant can self-fertilize.
C) the plant can be cross-fertilized.
D) plant fertilization could be controlled artificially.
E) the short life cycle of the pea plant.