Final answer:
The garden pea was optimal for Mendel's genetics experiments due to its easily observable traits, rapid life cycle, and natural self-fertilization which provided true-breeding strains.
Step-by-step explanation:
The garden pea, Pisum sativum, was an excellent choice for Gregor Mendel's inheritance experiments for several reasons. First, these pea plants have distinct, easily observable traits like plant height, seed texture, seed color, flower color, pea pod size, pea pod color, and flower position. Second, they are fast growing and reach maturity within one season, allowing for the observation of many generations in a brief period of time. Lastly, pea plants are naturally self-fertilizing, which leads to true-breeding strains that consistently produce offspring with parental traits, minimizing the appearance of unexpected variations.