Answer: Choice D. < B = < A
ie, "angle B = angle A"
The symmetric property is if y = x then x = y. The order of what is on the left or right side of the equation does not matter. It's like saying 2+3 = 5 is the same as 5 = 2+3.
This idea can be extended to congruences because congruent angles have the same measure.
So < A = < B is the same as < B = < A.
