C

Step 1: Understand the nature of an electric dipole in a non-uniform electric field.
An electric dipole consists of two equal and opposite charges separated by a distance. In a uniform electric field, the dipole experiences torque but no net force.
Step 2: Analyze the scenario in a non-uniform electric field.
In a non-uniform electric field, the electric field strength varies from one point to another. As a result, the positive charge of the dipole experiences a different force due to the electric field compared to the negative charge.
Step 3: The forces on the two charges lead to a net force acting on the dipole, resulting in a translational motion.
Additionally, the dipole also experiences torque about its center of mass because the electric field exerts different forces on the two charges.
Therefore, both a resultant force and torque are experienced by the dipole in a non-uniform electric field. Hence, the correct answer is:
Therefore, the correct option is C: a resultant force and a torque.