What is the main currency used in Mexico?

The primary currency used in Mexico is the Peso. It is the official monetary unit that facilitates transactions and trade within the country. The Peso has been the standard currency since the colonial period, evolving into the modern Mexican Peso, which is represented by the symbol "$" or "MXN" for its international code.

In contrast, other options like the Dollar, Euro, and Pound refer to currencies used in other countries. The United States Dollar is widely known and used in many contexts, but it is not the legal tender in Mexico. The Euro is the currency of the Eurozone, primarily used in European Union countries, and the Pound refers to the British Pound Sterling used in the United Kingdom. Hence, the Peso is the correct answer as it is the designated currency that citizens and businesses in Mexico use for daily financial transactions.