Which factors primarily drive the environmental changes observed in ecosystems?

The correct choice highlights that biotic and abiotic interactions are fundamental drivers of environmental changes in ecosystems. Biotic interactions involve living organisms, including competition, predation, and symbiotic relationships, which can significantly affect species populations and community structure over time. Abiotic factors encompass non-living elements such as temperature, water availability, soil composition, and sunlight, all of which contribute to the conditions under which organisms thrive or struggle.

Changes in these biotic and abiotic interactions can lead to shifts in ecosystem dynamics, influencing everything from nutrient cycling to energy flow. For example, a change in temperature due to seasonal shifts can affect species breeding cycles, while increased rainfall can alter plant growth patterns, which in turn impacts herbivores and their predators.

Considering the other options, while human intervention and climate change do significantly alter ecosystems, they are more specific manifestations of broader biotic and abiotic interactions. Similarly, while species prevalence and density play roles in specific ecosystems, they are influenced by the interactions outlined in the correct answer. Geological formations, while important, impact ecosystems primarily as abiotic factors but do not drive environmental changes on their own.