Which term describes an environmental factor that restricts the growth or activities of an organism?

The term that accurately describes an environmental factor that restricts the growth or activities of an organism is "limiting factor." This concept refers to any resource or environmental condition that limits the size of a population or the success of an organism within that population. For instance, factors such as food availability, water supply, habitat space, and climate conditions can all serve as limiting factors. These elements play a critical role in determining how well a species can thrive in a given environment, thereby influencing population dynamics and ecosystem stability.

In contrast, carrying capacity refers to the maximum number of individuals that an environment can sustainably support over time, and it is often affected by limiting factors. Reproductive isolation pertains to mechanisms that prevent mating or fertilization between different species, which is crucial in the context of speciation rather than individual organism growth. Adaptation refers to the process by which organisms develop traits that better suit them to their environment, which is a response to environmental pressures rather than a limiting factor itself. Thus, "limiting factor" is the most fitting term for the question posed.