Answer: frictional unemployment created by sectoral shifts.
Step-by-step explanation:
Frictional unemployment is the unemployment that exists in any economy as a result of people moving from one job to another. Frictional unemployment also called search unemployment as it is time that is spent between jobs when a worker is transferring from one job to another or searching for a job.
The sectoral shifts of labor demand across on the industries will lead to a flow of labor from the declining sector to an expanding sector which is why the bus companies will hire more drivers. This adjustment of labor to the new patterns of labor demand are typically slow and involves frictional unemployment.