Which figure is a counterexample to the following statement?

a quadrilateral with one pair of parallel sides is a parallelogram.

a. a right triangle has perpendicular sides.

b. a square is a rectangle.

c. a trapezoid is not a parallelogram.

d. a dart is not a parallelogram.

I'm terrible at math any here is appreciated.

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?