Step 1: Understanding the Question:
We need to identify the country from the list whose currency is the peso.
Step 2: Key Approach:
Check each option against its actual currency name, since the word peso has appeared in more than one country's currency history.
Step 3: Detailed Explanation:
Mexico has used the peso as its official, continuously named currency since Spanish colonial times, and the Mexican peso remains its legal tender today. It is the peso most commonly cited in trade and economics because of this long, stable history under one name.
Peru's official currency is the sol, not the peso, so option (2) does not fit.
Argentina has renamed its currency several times over its history, moving through the peso moneda nacional, peso ley, peso argentino, and austral before settling on the current peso convertible, so its currency history is far less settled under one continuous name than Mexico's.
Since Mexico is present in the list and clearly uses the peso, option (4), none of these, cannot be correct.
Step 4: Final Answer:
The peso is the currency of Mexico.