Answer:
A. ∠ABC ≅ ∠DBE
Explanation:
The whole proof is not shown, but in order to show the triangles similar, one would need to (a) show the sides are proportional, and (b) show the included angle is the same. The portion of the proof that is shown is on the way to showing side lengths are proportional. The missing part for showing triangle similarity is the congruence statement for angle B, as shown above.
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Once the triangles are shown to be similar, additional work is needed to show DE║AC. At least one pair of corresponding "base" angles must be shown congruent, too.