Zinc-copper couple that can be used as a reducing agent is obtained by:

Zinc coated with copper

The correct answer is option 1. Zinc coated with copper.

A zinc-copper couple is a type of electrochemical cell that can be used as a reducing agent. The zinc metal is the reducing agent, and the copper metal is the oxidizing agent.

When the zinc-copper couple is used, the zinc metal is oxidized and the copper metal is reduced. This means that the zinc metal loses electrons and the copper metal gains electrons.

The zinc-copper couple can be obtained by coating zinc metal with copper metal. The copper metal will protect the zinc metal from oxidation, and the zinc metal will be available to be oxidized when needed.

The other options are incorrect.

Option (2) is incorrect because zinc and copper wires welded together will not form a zinc-copper couple.

Option (3) is incorrect because mixing zinc dust and copper gauze will not form a zinc-copper couple.

Option (4) is incorrect because copper coated with zinc will not form a zinc-copper couple.