A Charge Q Is Spread Uniformly Along the Circumference of a Circle

Multiple Choice

A charge Q is spread uniformly along the circumference of a circle of radius R. A point particlewith charge q is placed at the center of this circle. The total force exerted on the particle q can be calculated by Coulomb's law:

A) just use R for the distance
B) just use 2R for the distance
C) just use 2 $\pi$ R for the distance
D) result of the calculation is zero
E) none of the above