- AThey are equal.
- BThey are complementary.
- CThey are vertically opposite, so they are equal.
- DThey are supplementary.
Step-by-Step Solution
Between the parallels and on the same side of the transversal describes CO-INTERIOR (allied) angles, and these sum to 180°. Trap: the first option is the single most common error in this chapter — co-interior angles are supplementary, not equal. Vertically opposite angles share a vertex, which this pair does not.
Answer: D) They are supplementary.