OP=OS
∠Q=∠R
∠P=∠S
PQ=SR
Given OQ=OR and △POQ ≅ △ROS
We know that, congruent parts of congruent triangles are congruent
∠POQ ≅ ∠ROS (vertically opposite angles)
If OP=OS then by using the (SAS) congruent, we can conclude the congruency of two triangles.
Hence, option C is sufficient to prove the congruency.