## Detection Note
The validator flagged this with error `TABLE_FORMAT`:
> Spec uses LaTeX aligned environment (flagged as table/array-style formatting) and includes exam metadata '[Single Correct Type, 2017 Adv.]'.
## Question to Fix
Let O be the origin and let PQR be an arbitrary triangle. The point S is such that
OP⋅OQ+OR⋅OS=OR⋅OP+OQ⋅OS=OQ⋅OR+OP⋅OS.
Then the triangle PQR has S as its
(1) centroid
(2) orthocentre
(3) incentre
(4) circumcentre