We are given that ∠B ≅ ∠C. Assume segment AB is not congruent to .

In a triangle, congruent angles are opposite congruent sides. ∠B is opposite segment AC, and ∠C is opposite segment AB, so ∠B ≅ ∠C implies AC ≅ AB. Therefore the assumption is that segment AB is not congruent to segment AC, choice A.

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