Final answer:
The best example of direct human-environment interaction is a factory releasing pollutants into a river, as it immediately affects the ecosystem and exemplifies the direct impact humans can have on nature.
Step-by-step explanation:
The direct human-environment interaction that best exemplifies our influence on nature is C) A factory releasing pollutants into a river. This directly affects the ecosystem by introducing harmful substances that can cause damage to wildlife and disrupt natural processes. Other examples of human-environment interactions include the use of organic fertilizers, which modifies the nutrient content of the soil, and conservation efforts like recycling programs and water usage reduction. Nonetheless, the immediate release of pollutants into a natural water source is a stark and direct interaction that often results in evident ecological changes such as water pollution, harm to aquatic life, and long-term damage to ecosystems.