Final answer:
Triangles can be determined to be congruent by comparing the lengths of their sides, even without knowing the measures of all angles. This can be done using the Side Congruency Theorems.
Step-by-step explanation:
The answer is b) Side.
Triangles can be determined to be congruent by comparing the lengths of their sides, even without knowing the measures of all angles. This can be done using the Side Congruency Theorems. These theorems state that if the corresponding sides of two triangles are congruent, then the triangles themselves are congruent. This means that if two triangles have the same lengths for their corresponding sides, they are guaranteed to be congruent.