This is because complementary angles add up to 90 degrees. In this example, the angles are exactly 45 degrees. Therefore, because there are two angles 45 * 2 is 90. Answer is B.
We can rule out A and B because they wont equal 180 or 90 they will be somewhere in between. We can rule out C because those are acute angles. So we are left with D. These angles are vertical because they are opposite angles made by two intersecting lines and they have equal values.
