Final answer:
The electric field at a point just inside the hollow conducting sphere is zero due to the redistribution of charges in a conductor at electrostatic equilibrium. Therefore, the correct option is A.
Step-by-step explanation:
The electric field at a point just inside the hollow conducting sphere is zero. This conclusion is based on the principle that the charges on a conductor in electrostatic equilibrium redistribute themselves in such a way that the electric field within the conductor and just under its surface is zero. This is because the electric field within a conductor would cause the free charges to move - which cannot happen in an equilibrium state. By applying Gauss's Law over a closed spherical surface within a conducting material, we find that there must be no electric field inside the material. Therefore, the correct answer is A) Zero.