1. Disguised unemployment, also known as hidden unemployment, is a situation where more people are engaged in an activity (typically agriculture in developing economies) than are actually required.
2. While these people appear to be employed, their contribution to the total output is very little or negligible. If some of these workers are withdrawn from the activity, the total output will not decrease.
3. This implies that the marginal productivity of labour (the additional output produced by employing one more worker) is zero or very close to zero.
4. Option (A) describes general unemployment, not specifically disguised unemployment.
5. Option (B) might be a contributing factor to disguised unemployment but is not its definition.
6. Option (D) describes low productivity in general, whereas disguised unemployment specifically refers to the marginal productivity being zero.