Three identical point charges q are placed at three vertices of a square of side a. The electric potential energy of the system is: (a) U₁ =k(4+√√2) a (c) U₁ = k(4+√√2) 2a (b) U₁ = k²² (4+ √2) =k(4+√2) 2a (d) U₁ = k²² (4+ √2) a