Explanation:

Gregor Mendel, often referred to as the 'father of modern genetics', conducted his groundbreaking experiments on inheritance using the common garden pea, *Pisum sativum*. He chose garden peas due to their distinct observable traits, short generation time, and ease of controlled cross-pollination. Option C, Garden pea, is the correct answer. Option A, edible pea, is a general term and not specific enough. Option B, wild pea, refers to various wild species of peas, which Mendel did not use. Option D, pigeon pea (*Cajanus cajan*), is another legume species, but it was not the subject of Mendel's famous experiments.