Can someone please help? Thanks! The answer that I have marked is incorrect, im making corrections

It is D.

Explanation:

The compass needle pointed in the direction of the current's magnetic field.

a charge 3q is at the origin, and a charge −2q is on the positive x axis at x=a. part a where on the x-axis would you place a third charge so it would experience no net electric force? enter an expression for the exact answer, which will involve a square-root sign. (do not enter an approximate decimal answer.)