Write chemical equations to highlight the Gattermann-Koch reaction of benzene followed by the Cannizzaro reaction.

a) ( C₆H₆ + CO + HCl → C₆H₅CHO + HCl ), ( C₆H₅CHO + OH⁻ → C₆H₅COOH + H₂ )
b) ( C₆H₆ + CO + HCl → C₆H₅COCl + H₂ ), ( C₆H₅COCl + NaOH → C₆H₅CHO + NaCl + H₂O )
c) ( C₆H₆ + CO + HCl → C₆H₅COOH + H₂O ), ( C₆H₅COOH + NaOH → C₆H₅CHO + NaCl + H₂O )
d) ( C₆H₆ + CO + H₂O → C₆H₅COOH + HCl ), ( C₆H₅COOH + NaOH → C₆H₅CHO + NaCl + H₂O )