Final answer:
The scientist who experimented with pea plants before Gregor Mendel was Pierre Louis Maupertuis (option D).
Step-by-step explanation:
The scientist who worked on garden pea before Gregor Mendel was Pierre Louis Maupertuis (option D). Mendel is known for his groundbreaking work in genetics and his experiments with pea plants. His work laid the foundation for the field of genetics, establishing the fundamental principles of heredity. Mendel conducted his experiments at the Augustinian Abbey of St. Thomas in Brno, using pea plants as his model system.
His observation that traits are transmitted from parents to offspring in discrete and predictable patterns including dominant and recessive forms changed the way we understand inheritance. However, before Mendel, there were other scientists such as Maupertuis who also studied inheritance patterns.