Explanation:

- Gross National Product (GNP) at Factor Cost: Total value of goods and services produced by a country's residents, minus indirect taxes plus subsidies, but before accounting for depreciation.

- Gross National Product at Market Price: Includes indirect taxes but doesn't consider depreciation or subsidies in its calculations.

- Net National Product (NNP) at Factor Cost: Often referred to as National Income, as it subtracts depreciation from GNP at factor cost, aligning closely with actual income of residents.

- Net National Product at Market Price: Similar to GNP at market price, adjusting for depreciation.

Correct Answer: Option 3: Net National Product at Factor Cost.