Answer:
D. One
Step-by-step explanation:
A parallelogram will have two sets of equal sides. Since we have that fact, all we need to know are the angles.
A quadrilateral will have a total of 360° in its angles. If only one angle is equal to 90°, then we can do the math to figure out that all the others must be 90° as well. A rectangle is a parallelogram with the opposite sides being parallel and all the angles being 90°. This then answers the question.
"The Math"
-> Keep in mind there will be four angles
-> Once we subtract the first angle of 90°, we will have three angles left. Hence why we divide by 3.
360° - 90° = 270°
270° / 3 = 90° ✓
