Answer: choice 2) SAS
AB = DE is one pair of congruent sides that forms the first S in SAS. The other S in SAS refers to the pair of congruent sides BC = EF. The A in SAS is the angle pair angle B = angle E. Note how angle B and angle E are between the two pairs of congruent sides. The order of the letters matters because SAS is different from SSA, which is not a valid congruence argument. Check out the attached image.
