Which decision could humans make that would help the environment the most? A. Use electricity instead of gas
B. Eat more manufactured foods and less farmed foods
C. Use less energy and fewer goods
D. Care for beautiful gardens

A:Use electricity instead of gas.

Explanation:

Hopefully this helps

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.