Structural unemployment is caused by

a. temporary layoffs in industries such as construction.

b. shifts in the economy that make certain job skills obsolete.

c. short-term changes in the economy.

d. the impact of the business cycle on job opportunities.

B) shifts in the economy that make certain job skills obsolete.

Explanation:

There are three types of unemployment:

Structural Unemployment (involuntary) : the skills of the worker do not match the skills required by employers. Cyclical Unemployment (involuntary) : slow economic growth or economic contraction cause that employers require less workers. Frictional Unemployment (voluntary) : someone quits his/her job voluntarily because they are searching for a better job, or new workers enter the labor force.