Final answer:
Geophysics and Geography are the most useful scientific fields for investigating human activities and their impact on the environment. So the correct option is D.
Step-by-step explanation:
The pair of scientific fields that would be most useful in investigating human activities and their impact on the environment are Geophysics and Geography.
Geophysics is the study of the Earth's physical properties and processes, including the study of earthquakes, volcanoes, and plate tectonics. It can help us understand the geological factors that affect the environment.
Geography, on the other hand, focuses on the study of the Earth's landscapes, environments, and societies. It can help us understand human activities and their impact on the environment, such as deforestation, urbanization, and climate change.