What was the primary focus of Malthus’s work?

Malthus's work primarily centered around the concept of population growth and its consequences. He famously theorized that populations tend to grow exponentially while food production increases arithmetically, which leads to a situation where the population can outstrip its food supply. This imbalance could result in famine, disease, and other societal issues, a theory he outlined in his seminal work, "An Essay on the Principle of Population." His argument was that unchecked population growth would inevitably lead to resource depletion, which would have dire consequences for society.

The other options, while important themes in other contexts, do not encapsulate Malthus's primary focus. Climate change, industrialization, and agricultural techniques were not the central themes of his theories, thus allowing his exploration of population dynamics to stand as the cornerstone of his contributions to economic and social thought.