Answer: (B). nuclie experiences a force to the right and electron experiences a force to the left.
Explanation: The nuclie is positively charged and so it will experience a force in the same direction as the direction of the Electric Field {in this case to the right}
On the otherhand, the electrons which are negatively charge will experience a force in opposite direction to that experienced by the nuclie which is positively charged. So the electron experiences a force to the left.
I believe this is clear.