Concept:National income is underestimated when some productive activities are not included in recorded market transactions.
Explanation:Rapid decrease in prices can reduce the money value of output and cause under-recording.
Increased subsistence production is not sold in the market, so it often escapes measurement.
Unpaid services are not exchanged for money, so they are also left out of national income accounts.
Specialisation of labour encourages market exchange of goods and services, making output easier to count.
Therefore, specialisation of labour does not lead to an underestimation of national income.
Answer:C. Practice of specialisation of labour