Forests are useful in fighting the effects of air pollution because they produce A. carbon B. oxygen C. hydrogen D. carbon dioxide Please select the best answer from the choices provided. Please answer for my test

oxygen

Explanation:

as trees grow they produce oxygen so we can breathe the air

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.

answer; people have no objective standard by which to judge themselves;