Answer:
The correct answer is 3
Explanation:
The capacitance in a capacitor is
      C = ε₀ A / d
When we separate the capacitors the capacitance decreases
Let's look for capacitance
    C₀ = ε₀  A / d
    C = ε₀  A / D
    Â
The relationship between the two capacitances is
    C / C₀ = d /D
The energy stored in a capacitor is
      U = ½ C ΔV²
If we maintain the same potential difference, the stored energy decreases if the capacitance decreases
The correct answer is 3
The relationship between the two energies is
     U₀ = ½ ε₀  A / d ΔV²
     U = ½ eo A / D ΔV²
     U / U₀ = d/D