Which pair of triangles can be proven congruent by SAS?

Which pair of triangles can be proven congruent by SAS?

Ans. The correct answer is B.

The diagram presents one triangle, ?ABC, and line segment AD forming two small triangles, ?ADB and ?ADC. The notation presents side AD as a common side to both triangles (hence is equal to itself), ∠ADB and ∠ADC as right angles (thus equal to each other), and side BD as equal to side DC (indicated by an independent dash). Thus, by the Side-Angle-Side (SAS) rule of congruence, the two triangles, ?ADB and ?ADC, can be established as congruent.