torque question

1. The problem statement, all variables and given/known data

A 12-N force is applied at the point x=3m, y=1m. Find the torque about the origin if the force points in (a) the x direction, (b) the y direction, and (c) the z direction.

3. The attempt at a solution

a) Attachment 68242

The answer for (a) is 12Nm which is correct. However, I am unsure why the distance r must be extended down the the x-axis. Can it not be extended upward instead of downward?
Also, I do know how to use the right hand rule but how should I apply it to this question?

Attached Images
File Type: png Untitled.png (7.9 KB)

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