Answer:
(B) Reflexive property
Step-by-step explanation:
To prove: If the quadrilateral ABCD is a parallelogram, then its opposite sides are congruent.
Proof:
Statement Reason
1. AB is parallel to DC Definition of parallelogram
and AD is parallel to BC
2.∠1=∠2
and ∠3=∠4 If two parallel lines are cut by a transversal then the alternate interior angles are congruent
3. BD=BD Reflexive property
4. ΔADB≅ΔCBD If two angles and the included side of a triangle are congruent to the corresponding angles and side of another triangle, then the triangles are congruent
5. AB = DC,
AD = BC Corresponding parts of congruent triangles are congruent
Hence proved
Thus, option B is correct.
