A High speed digital subsystem requires three voltages V₁, V₂ and V₃ with 1 : 2 : 1 power ratings, respectively. The power supply is designed with the distribute power conversion scheme as shown in the following figure. What is the overall power conversion efficiency?

A. $$\frac{{4 \times {\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + 2 \times {\eta _3} + {\eta _2}}}$$

B. $$\frac{{{\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + 2 \times {\eta _3} + {\eta _2}}}$$

C. $$\frac{{4 \times {\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + {\eta _2} + {\eta _3}}}$$

D. $$\frac{{2 \times {\eta _1} \times {\eta _2} \times {\eta _3}}}{{{\eta _2}{\eta _3} + {\eta _2} + {\eta _3}}}$$

Answer: Option A