Disguised unemployment generally means

Disguised unemployment refers to a situation where people are employed but are not contributing to the production process effectively. This happens when more people are engaged in a task than are actually needed. The marginal productivity of labour, which is the additional output generated by employing one more worker, becomes zero in such cases. Removing some workers wouldn't decrease the total output. Option A: (a) large number of people remain unemployed - This describes general unemployment, not disguised unemployment. General unemployment means people are actively seeking work but cannot find it. Option B: (b) alternative employment is not available - Lack of alternative employment contributes to unemployment generally, but doesn't define disguised unemployment. Option C: (c) marginal productivity of labour is zero - Correct. This is the defining characteristic of disguised unemployment. Option D: (d) productivity of workers is low - While disguised unemployment often *results* in low productivity, low productivity itself isn't the definition of disguised unemployment. It's the zero *marginal* productivity that's key.