Design a 4 bit Gray-to-BCD code converter circuit. The circuit has also a fifth output P (odd parity generator for the BCD code). Use 4-to-1 MUXs (multiplexers) and a gate minimum external logic.

I wrote down (using this guide) the truth table for the Gray code to BCD converter but I couldn't design 4:1 MUXs and a gate minimum external logic. How many 4:1 MUXs are there and what about the gate minimum external logic?