Work of a Particle in the XY Plane

[Redfire66]

Homework Statement

A force acting on a particle moving in the xy-plane is F = (2yi + 1.2x^2 j)N. where x and y are in meters. The particle moves from the origin to a final position having coordinates x = 5m and y = 5m. Calculate the work done by F along OAC

Homework Equations

Integral of force by distance
W = ∫(Fxdx + Fydy)

The Attempt at a Solution

I have the answer. And I know what they did. But what I don't understand is how it makes sense.
The solution involves breaking up the integral into two partitions, Woa and Wac.
This is what I don't really understand - how is the work on OA zero? There is a force acting in the x direction and it moves from O to A. So by definition, since there is a force acting over a distance there should be work right? (Unless I'm not reading this properly)

 

[ehild]

Where are points A and C?