How many degrees has abc been rotated about the origin?

 The correct option is (A) 90°.

Step-by-step explanation:  We are given to find the number of degrees by which the triangle ABC has been rotated counterclockwise about the origin.

From the graph, we note that

the co-ordinates of the vertices of triangle ABC are A(-8, 6), B(-5, 9) and C(-2, 6).

And, the co-ordinates of the vertices of the rotated triangle A'B'C' are (-6, -8), B(-9, -5) and C(-6, -2).

That is, the transformation is as follows :

(x, y)   ⇒    (-y, x).

Since this is the transformation rule for 90 degrees counterclockwise, so the required number of degrees is 90 degrees.

Option (A) is CORRECT.

f is the midpoint of