Charles Darwin hypothesized that some individuals would be better equipped for survival than others, and that those that were less equipped would not survive. Darwin formulated this hypothesis based on the work of which scholar?

John Gould, who compared mainland and island finches
Thomas Malthus, who studied population growth
Sir Isaac Newton, who formulated the laws of motion
Gregor Mendel, who determined genetic inheritance of traits

Thomas Malthus, who studied population growth.