Final answer:
Arthur Holmes and Harry Hess provided supporting evidence and mechanisms that helped validate Alfred Wegener's theory of continental drift, which later evolved into the theory of plate tectonics.
Step-by-step explanation:
The scientists who brought forth supporting evidence to Alfred Wegener's theory of continental drift and later helped develop the theory of plate tectonics were Arthur Holmes and Harry Hess. Wegener himself provided significant evidence for his theory, such as the jigsaw fit of continents, matching fossils across oceans, corresponding mountain ranges, and paleoclimatic data suggesting that continents were once located in different climate zones. However, he lacked an explanation for the mechanism behind the drift.
Arthur Holmes expanded on Wegener's hypothesis by suggesting mantle convection as a possible mechanism for continental movement. Harry Hess later provided further evidence, contributing to the acceptance of the theory with his concept of seafloor spreading in the 1960s. This was a critical step in the scientific community's eventual acceptance of the idea of a dynamic Earth with shifting continents. Thus, option A, Alfred Wegener and Arthur Holmes, is the appropriate choice to answer the student's question.