Which Characteristic of Pea Plants Were Important in Their Selection

Which characteristic of pea plants were important in their selection as Mendel's research organism?

A) Peas are easy to cultivate.
B) Pea plants have a short generation time.
C) Pea plants are self-pollinating but can be cross-fertilized easily.
D) Many true-breeding varieties were available.
E) All of the above were important characteristics in Mendel's selection.