Which reason justifies the statement that angle KLC is complementary to angle KJC ?

If ∠KLC and ∠KJC are each complementary to the same angle, then each adds with that angle to make 90°. Therefore they are congruent to each other, and the relevant reason is that angles congruent to the same angle are complementary to that same angle. Choice D states this reason; choice A incorrectly says they are supplementary.

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