Let O be the origin and let PQR be an arbitrary triangle. The point S is such that $$\overrightarrow{OP}.\overrightarrow{OQ}+\overrightarrow{OR}.\overrightarrow{OS}=\overrightarrow{OR}.\overrightarrow{OP}+\overrightarrow{OQ}.\overrightarrow{OS}=\overrightarrow{OQ}.\overrightarrow{OR}+\overrightarrow{OP}.\overrightarrow{OS}$$ Then the triangle PQR has S as its

A

centroid

B

circumcentre

C

incentre

D

orthocenter