Of the three metals, #Pb, Cu, Zn#, which is the most active?
Zinc. Copper is the least active of these three.
I base this choice on the one type of reaction that metals typically undergo - oxidation.
If you consult a list of what is known as "reduction potential", and which is very useful in determining the manner in which chemicals oxidize or reduce, you find that zinc is considerably more prone to oxidation that is lead, which in turn is more prone to oxidation that copper.
Copper, in fact is known as a noble metal, and is fairly resistant to oxidation, while zinc is one of the most easily oxidized of metals. For this reason, it is commonly used as the anode (site of oxidation and source of electrons) in an electrochemical cell (such as a dry cell battery).