What is the force felt by the electrons and the nuclei in the rod when the external field described in the problem introduction is applied? (ignore internal fields in the rod for the moment.)

"The nuclei experience a force to the right and the electrons experience a force to the left"

Explanation:

The oppositely charged particles will start attracting each other, on the other hand the like particles will start repelling one another. Electrons are placed in such a manner in the orbit which is near the nucleus by the electromagnetic force, and hence the nucleus present in the center of the atom is positively charged and are attracted towards the negatively charged atoms. The electric and magnetic force helps electrons to hold on the atoms.

b would be the answer