The correct answer is (c) T.R. Malthus.
Thomas Robert Malthus (1766-1834) was an English economist and demographer. He is best known for his work on population, which he published in his 1798 book An Essay on the Principle of Population. In this book, Malthus argued that population growth is exponential, while the growth of food production is arithmetic. This means that population will eventually outstrip food production, leading to famine and poverty.
Malthus’s theory was controversial at the time, and it remains so today. Some people argue that Malthus was wrong, and that population growth can be controlled through economic development and technological innovation. Others argue that Malthus was right, and that we are facing a crisis of overpopulation.
The other options are incorrect. Charles Darwin (1809-1882) was an English naturalist who is best known for his work on evolution. A.R. Wallace (1823-1913) was a British naturalist who independently developed the theory of evolution by natural selection. J.J. Christian is not a well-known figure in the history of population theory.