The stepwise formation of \(\left[ Cu \left( NH _{3}\right)_{4}\right]^{2+}\) is given below \(Cu ^{2+}+ NH _{3} \stackrel{ K _{1}}{\rightleftharpoons}\left[ Cu \left( NH _{3}\right)\right]^{2+}\) \(\left[ Cu \left( NH _{3}\right)\right]^{2+}+ NH _{3} \stackrel{ K _{2}}{\rightleftharpoons}\left[ Cu \left( NH _{3}\right)_{2}\right]^{2+}\) \(\left[ Cu \left( NH _{3}\right)_{2}\right]^{2+}+ NH _{3} \stackrel{ K _{3}}{\rightleftharpoons}\left[ Cu \left( NH _{3}\right)_{3}\right]^{2+}\) \(\left[ Cu \left( NH _{3}\right)_{3}\right]^{2+}+ NH _{3} \stackrel{ K _{4}}{\rightleftharpoons}\left[ Cu \left( NH _{3}\right)_{4}\right]^{2+}\) The value of stability constants \(K _{1}, K _{2}, K _{3}\) and \(K _{4}\) are \(10^{4}, 1.58 \times 10^{3}, 5 \times 10^{2}\) and \(10^{2}\) respectively. The overall equilibrium constants for dissociation of \(\left[ Cu \left( NH _{3}\right)_{4}\right]^{2+}\) is \(x \times 10^{-12}\) The value of \(x\) is ............... (Rounded off to the nearest integer)

1. A \(3\)
2. B \(1\)
3. C \(5\)
4. D \(7\)