Friedrich Ratzel compared the development of a state to which of the following?

Friedrich Ratzel, a German geographer, is known for his organic theory of the state, which likened the development of a state to that of a biological organism. In this analogy, Ratzel suggested that states, like living organisms, go through a life cycle that includes stages of growth, development, and decline. He argued that just as an organism needs resources from its environment to sustain life and grow, a state requires resources to thrive and expand.

This perspective emphasizes the importance of a state's interactions with its geopolitical environment and suggests that states are dynamic entities that adapt to changing conditions, similar to how organisms respond to their physical surroundings. Ratzel’s ideas laid the groundwork for later geographic theories and were influential in the fields of political geography and geopolitics, where the relationship between a state's physical geography and its power and influence is examined.

In contrast, the other options do not align with Ratzel’s comparisons. Mechanical systems do not embody the dynamic, adaptive qualities associated with living organisms. Cultural diffusion pertains to the spread of cultural elements between societies, which is a different concept altogether. Economic systems, while integral to the functioning of states, do not encapsulate the biological analogy that Ratzel proposed.