C

To determine the angle at which the torque is maximized for an electric dipole in a uniform electric field, we use the formula for torque:
Torque (τ) = p × E
where p is the dipole moment and E is the electric field.
The torque is maximum when the angle θ between the dipole moment vector and the electric field is 90 degrees (i.e., cos(θ) = 0).
Thus for maximum torque, the angle between the dipole and the electric field must be θ = 90°.
Therefore, the correct option corresponding to this angle is C.