Ineed !

"a quadrilateral is a trapezoid if and only if it has exactly one pair of parallel sides."

if this statement is true, then which of the following statements must also be true?

a. a trapezoid has exactly one pair of parallel sides if and only if it is a quadrilateral.

b. a quadrilateral has exactly one pair of parallel sides if and only if it is a trapezoid.

c. a quadrilateral is not a trapezoid if and only if it has exactly one pair of parallel sides.

d. a quadrilateral does not have exactly one pair of parallel sides if and only if it is a trapezoid.