Which statement is always true? a cross section parallel to the base of a right rectangular prism is a square. a cross section perpendicular to the base of a right rectangular prism is congruent to the base. a cross section parallel to the base of a right rectangular prism is congruent to the base. a cross section perpendicular to the base of a right rectangular prism has the same dimensions as the base.

From the given statements in this item, what is always true is that the cross section of parallel to the base of the right rectangular prism is congruent to the base. The answer is the third choice. This is because when we cut through any part of the prism parallel to the base, the shape of the cross section is the same as the base. 

Step-by-step explanation:

answer: (c) m∠qpo + (2x + 16)° = 180°

step-by-step explanation:

the opposite angles of a quadrilateral are supplementary.

so, ∠o + ∠q = 180°   and   ∠p + ∠r = 180°

since ∠r = 2x + 16°, we can use substitution as follows:

∠p + ∠r = 180°

∠p + (2x + 16)° = 180°