Technological unemployment refers to the loss of jobs caused by technological change, such as the automation of tasks previously performed by humans. Option A exemplifies this concept by describing a scenario where robots replace human workers on assembly lines, directly leading to job losses. Option B does not represent technological unemployment because it describes an increase in productivity without a reduction in the workforce. Option C describes outsourcing, which is a different economic phenomenon related to labor cost reduction rather than technological change. Option D involves technological change but focuses on the need for additional training rather than job displacement.