. Consider a uniform spherical charge distribution of radius R1 centred at the origin O.

Consider a uniform spherical charge distribution of radius R₁ centred at the origin O. In this distribution, a spherical cavity of radius R₂, centred at P with distance OP = a = R₁ - R₂ (see figure) is made. If the electric field inside the cavity at position  is  then the correct statement(s) is (are)