The correct option is D Pea plants
Mendel studied the common garden pea plant, Pisum sativum because it was easy to cultivate and had a relatively short life cycle of 3 months. The plant exhibited discontinuous characteristics such as flower color and pea texture. Owing to its anatomy, it was easy to control the self-pollination of the plant and cross-fertilization between desired parents could be accomplished artificially. The presence of pure breeding varieties and easily visible contrasting characters and presence of F1 fertile hybrids were the additional advantageous characters for which Mendel chose garden pea as experimental material. Thus, the correct answer is option D.