Explanation:

- Studying the Vedas: According to Dharmashastras, studying the Vedas is a duty of all the "twice-born" classes, which include Brahmins, Kshatriyas, and Vaishyas. So, Vaishyas are indeed prescribed to study the Vedas.

- Engaging in trade: Engaging in agricultural work, cattle rearing and trade is traditionally considered a duty of Vaishyas. They are expected to contribute to economic activity, making this a prescribed duty.

- Option 1 (1 only): This would mean Vaishyas are only supposed to study the Vedas.

- Option 2 (2 only): This implies Vaishyas are meant to only engage in trade.

- Option 3 (Both 1 and 2): This correctly identifies both duties as applicable to Vaishyas.

- Option 4 (Neither 1 nor 2): This is incorrect as both activities are relevant.