Reduction of Metal Oxides to Metals

What is the incorrect reason for the statement "In many reactions, hydrogen acts as a reducing agent but it is not widely used as a reducing agent for metal extraction"?

The reducing agent used for the extraction of $\mathrm{Mo}$ and $\mathrm{W}$ is _____.

(A) ${\mathrm{H}}_2$
(B) $\mathrm{CO}$
(C) ${\mathrm{H}}_2\mathrm{S}$

Enter your correct answer as A, B or C.

Discuss the reduction of metal by hydrogen.

Write the formula of iron pyrites?