Answer:
Coplanar
Explanation:
We know that the collinear points are the points which together make a straight line. From the diagram, it is clearly visible that points R, T, and B make a straight line but C doesn't follow the path of RTB.
So it not collinear.
We know that that coplanar points are the points which together make a closed shapes in two-dimensions. From the diagram, it is clearly visible that points R, T, B, and C make a closed shape like a triangle.
So it is coplanar.