Final answer:
Mendel chose pea plants for his experiments because of their rapid reproduction, ease of cultivation, and true-breeding characteristics, but not for their small size.
Step-by-step explanation:
Gregor Mendel selected pea plants for his genetics experiments for several reasons but not for their small size. The ease of cultivation, variability in traits, and rapid reproduction are the true factors. Pea plants, such as Pisum sativum, are fast-growing and easy to raise, with clear dominant and recessive forms of traits—an essential aspect for studying inheritance. These plants also exhibit true-breeding characteristics, meaning they consistently produce offspring with traits that match the parent, which simplifies the analysis of hereditary patterns. Moreover, Mendel could cultivate large quantities of peas in a single season, allowing for observation of multiple generations in a short period, providing statistically significant results.