Choose the two situations that describe volume. A. measuring the length and width of a box
B. finding the total number of cubes a box will hold
C. counting how many blocks make up a block tower
D. measuring the length of each side of a desk using cubes
E. counting the number of cubes it takes to cover the entire surface of a desk

What is it?

B and C are volume

A = area/perimeter

D = Perimeter

E = surface area

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.