Lamarck's theory of evolution, often called the theory of the inheritance of acquired characteristics or the "use and disuse" theory, posits that traits developed during an organism's lifetime due to environmental pressures or how frequently a body part is used and can be passed on to its offspring.

A. Darwin: Charles Darwin's theory of evolution centered on natural selection, where individuals with advantageous, heritable traits (determined by random variation, not acquired in a lifetime) are more likely to survive and reproduce. While Darwin did mention the idea of "use and disuse" as a possible supplementary mechanism, it was not the main focus of his theory, and modern evolutionary science has largely discredited the inheritance of acquired physical characteristics.

B. Mendel: Gregor Mendel is known as the father of modern genetics. His work with pea plants established the fundamental laws of inheritance (how traits are passed from one generation to the next via discrete units, later called genes), which helped to supplant Lamarckian ideas and laid the foundation for the modern synthesis of evolutionary theory.

C. Morgan: Thomas Hunt Morgan was a prominent geneticist whose experimental work with fruit flies provided crucial evidence for the chromosome theory of inheritance, further solidifying the principles of genetics and moving evolutionary theory away from Lamarckism.