The blue pair is mentioned in option C, so option C is true.
The green pair is mentioned in option A. Since vertical angles are congruent, option A is also true.
Linear Pair
Any angle marked blue together with any angle marked green form a straight angle, so they are a linear pair. One of these pairs is mentioned in option B, so option B is true.
Conclusion
Since options A, B, and C are true, option D is the one that does not have to be true. In fact, ∠ BCE and ∠ ECD are supplementary, they are never complementary.
