The answer is F.
An unsaturated zone is the portion of the subsurface above the ground water table where air as well as water are present in its pores.
Therefore the statement is false as the pores would not be totally filled with water.
Hope it helps!
By rename do you mean turn into an improper fraction?
if so, it is because without turning it into an improper fraction, you cannot subtract 3/4 from 1/4 because you would get a negative answer and that would be incorrect