Final answer:
Part-time, temporary, and contract workers hired on an as-needed basis are known as a contingent workforce. Temp agencies, by providing jobs and temporary placements, help reduce the natural rate of unemployment and serve as a bridge to full-time employment.
Step-by-step explanation:
Part-time, temporary, and contract workers who are available for hire on an as-needed basis are known as D) a contingent workforce. The term 'contingent workforce' refers to those workers who are not permanent or full-time employees but are hired as and when required. Temp agencies have contributed to the rise of the contingent workforce, by acting as a medium between these workers and potential employers.
The flexibility of the contingent workforce allows for better alignment of labor needs with demand fluctuations. During economic downturns, businesses may prefer hiring from the contingent workforce rather than incurring the costs associated with hiring full-time workers. This preference can help reduce both frictional unemployment and the natural rate of unemployment, as it provides employment opportunities for people looking for permanent positions and can serve as a stepping stone to full-time employment.