Answer:
(B) Thomas Malthus, who studied population growth
Step-by-step explanation:
Thomas Malthus published his essay entitled "An Essay on the Principle of Population As It Affects the Future Improvement of Society" in 1798. Accordingly, the capacity of populations to increase geometrically leads to struggle for food, shelter and other resources. These negative processes put a check on the population size.
Darwin was influenced by the idea of ability of populations to exhibit exponential growth and struggle for existence. On the basis of the essay by Thomas Malthus, Darwin proposed that genetic variations allow only individuals with beneficial traits to survive the struggle.