Final answer:
Malthus and Marx disagreed on the causes of societal issues, with Malthus focusing on population growth and natural checks, and Marx on economic structures and class struggles. The correct option is b.
Step-by-step explanation:
The statement that is true of Malthus and Marx is that they disagreed about the root causes of overpopulation, poverty, and social upheaval. Thomas Malthus, an English clergyman, predicted that population growth would outpace food production, leading to widespread poverty. He saw nature's methods of war, famine, and disease as checks on population growth and advocated for families to have fewer children. Meanwhile, Karl Marx held very different views, believing that overpopulation was not the root of the problem, but rather the capitalist system and the class struggle it engendered.
While Malthus saw moral restraint and preventive checks as solutions to mitigate the crisis, Marx focused on the social and economic structures that led to inequitable wealth distribution. The disagreement between them was fundamental: Malthus thought that scarcity was inevitable due to population growth, while Marx saw it as a problem of distribution and production that capitalism exacerbated.
Hence, Option b is correct.