The correct answer is C. Only a torque but no net force.
An electric dipole consists of two equal and opposite charges separated by a small distance. When placed in a non-uniform electric field, the electric dipole experiences a torque, which tends to align the dipole with the electric field. This torque is given by the equation τ = pEsinθ, where τ is the torque, p is the dipole moment, E is the electric field strength, and θ is the angle between the dipole moment vector and the electric field vector.
However, the dipole experiences no net force in a non-uniform electric field. This is because the forces on the positive and negative charges are equal in magnitude and opposite in direction, resulting in a cancellation of the net force. Therefore, option D (No torque and no net force) is incorrect.
In summary, an electric dipole placed in a non-uniform electric field experiences only a torque (option C) but no net force.