For each case below, please state if the person mentioned is unemployed for Frictional, Structural, or Cyclical reasons. Please state your reasoning for each answer.
(a) Pak left his old job to go back to school and get his Master’s Degree, and now he is back in the job market looking for work.
(b) Sue just lost her job as a sales clerk at Macys due to low sales.
(c) John lost his job at the steel mill after the owner bought a robot to do John's job.
(d) Mary just lost her job as a teacher due to budget problems at the state level.