Final answer:
The sum of the measures of the interior angles of polygon QRST is 360°.
Step-by-step explanation:
A polygon QRST is a closed figure with four sides. To find the sum of the interior angles of a polygon, we use the formula (n-2) * 180, where n is the number of sides of the polygon. In this case, since QRST has four sides, n is equal to 4.
Therefore, the sum of the measures of the interior angles of polygon QRST is (4-2) * 180 = 2 * 180 = 360°. So the correct answer is D) 360°.