During the rule of the Mauryas, the materials used for minting coins were copper and bronze. Option 1 (Gold and Silver) is incorrect because gold and silver were not commonly used for minting coins during this time period. Option 2 (Silver and Copper) is also incorrect because silver was not used for minting coins by the Mauryas. Option 4 (Gold and Copper) is also incorrect because gold was not used for minting coins by the Mauryas.

Therefore, the correct answer is option 3 (Copper and Bronze). Copper and bronze were the primary materials used for minting coins during the rule of the Mauryas. Coins minted from these materials were widely circulated as a medium of exchange during this period.