Final answer:
To avoid self-fertilization in his pea plants, Mendel had to do all of the above. He removed the anthers from some plants, pollinated them by hand with pollen from other parent plants, and grew the plants in a pollinator-free environment.
Step-by-step explanation:
To avoid self-fertilization in his pea plants, Mendel had to do all of the above.
Mendel was interested in studying the offspring of two different parent plants, so he had to prevent self-pollination. He achieved this by removing the anthers from the flowers of some plants. By manually transferring pollen from other parent plants to the stigma of the modified flowers, Mendel ensured cross-pollination, where pollen from one plant fertilizes another plant of the same species. Additionally, growing the plants in a greenhouse that did not contain pollinators, such as bees, further prevented self-fertilization.
By using these methods, Mendel was able to produce hybrid offspring and study the patterns of inheritance, which led to the development of his laws of inheritance.