Option (A) is true because when two straight lines intersect to each other we get two pair of vertically opposite angles and the angles opposite to each other is always equal.
Option (B) is also correct as If the sum of two angles is equal to 180°, then they are supplementary to each other.
Option (C) is also correct as If the sum of the two angles is equal to 90°, then they are Complementary to each other.
