In triangles ABC and DEF, AB = DE and AC = EF, then to make these two triangles congruent, we must have :

1. BC = DF

2. ∠A = ∠E

3. any of (1) and (2)

4. none of (1) and (2)

Given,

In triangle ABC and DEF,

AB = DE (Given)

AC = EF (Given)

According to option 1 :

BC = DF

In such case all three sides are equal.

Then both the triangles will be congruent by S.S.S. axiom.

According to option 2 :

∠A = ∠E

In such case two sides and the included angle will be equal.

Then both the triangles will be congruent by S.A.S. axiom.

Hence, option 3 is the correct option.