In a fuel cell there is direct conversion of mechanical energy into electricity.

a. a chemical reaction produces heat, which then produces electricity.
b. reduction takes place at the cathode.
c. there is oxidation, but no reduction.

C

Explanation:

A fuel cell uses both hydrogen and oxygen as fuels. At the cathode oxygen is reduced to water according to the equation

O2+4H^+ +4e >2H2O

And hydrogen is oxidized at the anode:

2H2>4H^+ +4e

Fuel cells produce only water as a by product hence they are environment friendly