The way that you tell which angles are congruent, are based on the angle marks. Angle A and C are congruent because they both contain 3 of the congruency marks, meaning they would equal the same degree. The answer is B because starting with angle BDA, B is your starting point, whereas D is the angle and A is the point you end on. With angle BAD, you start at point B and end at D, making angle A the one you're looking at. Because angle A contains 3 congruency marks, while angle B only contains one, this makes the two angles NOT congruent. Hope this helps. :)
