When scientists are doing research to determine how the environment affects a life form, it often takes many years to reach a conclusion. why do you think that is the case?

a. many environmental factors must be considered (water, light, and temperature were just three that were investigated in this simulation).
b. many tests must be performed because variables need to be tested one at a time (first test for water effects, then test for light effects,
c. some effects take a long time to become noticed, so the experiments often have to take place over long periods of time.
d. all