Explanation:

- Option 1: Purchase and Sale of Old Commodities

- Old commodities aren't included in GNP calculations as they don't contribute to current production. They're just a transfer of ownership for goods produced in the past.

- Option 2: Intermediate Commodities

- Intermediate goods, used in producing final goods and services, are excluded from GNP to avoid double counting. GNP only considers final products and services.

- Option 3: (a) and (b) both

- Both old commodities and intermediate goods aren't included in the GNP calculation.

- Option 4: None of the above

- This would mean all options are included in GNP, which is incorrect.

The correct choice is:

Option 3: (a) and (b) both