Explanation:

In this scenario, Ram agrees to sell all the mangoes which will be produced in his garden next year to Mohan. This type of agreement is known as a sale of future goods.

Future Goods:
Future goods refer to goods that are not in existence or not yet identified at the time of the contract. In other words, these are the goods that are not yet produced or acquired by the seller.

Unascertained Goods:
Unascertained goods refer to goods that have not been identified or set apart from the mass of goods at the time of the contract. These goods are not specifically identified and are not distinguished from other goods of the same kind.

Contingent Goods:
Contingent goods refer to goods whose acquisition or availability depends on the happening of a specific event. These goods are uncertain and their existence is dependent on a particular condition being fulfilled.

Ascertained Goods:
Ascertained goods refer to goods that have been identified and agreed upon by both the buyer and the seller. These goods are specific, identified, and distinguished from other goods of the same kind.

Explanation of the Answer:
The correct answer in this case is option 'B' - Future goods. The agreement between Ram and Mohan is for the sale of mangoes that will be produced in Ram's garden next year. As the mangoes are yet to be produced and are not currently available or identified, they fall under the category of future goods.

Since the mangoes are not yet in existence and have not been specifically identified, they cannot be classified as ascertained goods. Additionally, the mangoes are not contingent goods because their availability does not depend on the occurrence of any particular event. Similarly, they are also not unascertained goods as they will be produced in the future and have not been distinguished from other goods.

Hence, the correct categorization for the agreement between Ram and Mohan is the sale of future goods.