Among the following metals the number of metals that are extracted...

Self-Reduction Process: The cations of the less electropositive metals like Pb, Hg and Cu may be reduced without the use of any additional reducing agent.
Self-reduction of Cu:
$2C{u}_{2}O + C{u}_{2}S \to 6Cu + S{O}_{2}\left(g\right)$
It is called self-reducing because copper oxide itself reduced the copper sulfide to give copper and sulfur dioxide.
Similar reactions occurs for Pb and Hg.