Explanation:

- NDP at FC is Net Domestic Product at Factor Cost. It's a measure of the economic output of a country while accounting for the wear and tear on assets, or depreciation.

- GDP at FC is Gross Domestic Product at Factor Cost, which doesn’t deduct depreciation.

- Depreciation is the decrease in the value of an asset over time due to use, wear, or obsolescence.

- Option 1: Depreciation - the correct term to subtract from GDP at FC to get NDP at FC.

- Option 2: Indirect taxes are subtracted from GDP at market prices to obtain GDP at factor cost.

- Option 3: Net factor income from abroad relates to GNP, not NDP.

- Option 4: Subsidies are added to GDP at market prices to get GDP at factor cost.