What is always true about vertical angles?
a. the sum of vertical angles is always 180°
b. vertical angles combine to form a straight angle.
c. vertical angles are equal in measure.
d. the sum of vertical angles is always 90°.
subme

C

Step-by-step explanation:

(a)the sum of a vertical is always 180 this is true for liner angles not vertical angles.

(b) vertical angles combine to form a strategist angle, a straight angle is 180 so like in answer a this is talking about a liner angle not a vertical angle.

(c) this is ALWAYS true for vertical angles because, if they are not well it wouldn't be a vertical angle than.

(d) the sum of vertical angles is always 90 this is wrong its talking about a complementary angle not a vertical angle.