CAYLEY 2024 Problem 3

In \triangle A B C, points E and F are on A B and B C, respectively, such that A E=B F and B E=C F.

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If \angle B A C=70^{\circ}, the measure of \angle A B C is

Answer Choices
A. 40^{\circ}
B. 50^{\circ}
C. 60^{\circ}
D. 70^{\circ}
E. 30^{\circ}