Which experimental design decision would most likely produce invalid and unreliable results? having more than one controlled variable
having only one control group
having more than one independent variable
having only one experimental group

Explanation:

The independent variable determines the value that needs to be calculated or the decision that needs to be made from the observations of the experiment. Hence, experimental design decision would most likely produce invalid and unreliable results when having more than one independent variable.

the answer is trees if i'm not mistaken

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.