Answer : 3. "During the time of Buddha"
Explanation :

The first metal coins appeared in the time of Buddha and they are called ‘Punchmark’ and ‘Aahat’. Those mainly are made up of silver but some are of copper also. They are called Aahat because many symbols are inscribed on them. Such coins are Found in all over the country from Taxila to Magadha to Mysore.