Identify whether each of the following reflects seasonal, structural, frictional, or cyclical unemployment.
a. A sales employee is laid off due to slow business after consumer spending falls.
b. An automotive worker is replaced by robotic equipment on the assembly line.
c. A salesperson quits a job in California and seeks a new sales position after moving to New York.
d. An employee is fired due to poor job performance and searches the want ads each day for work.