Which of the following is a difference between regular $($full$-$time$)$ employees and contingent workers?

Unlike contingent workers, regular employees offer flexibility in the type of resources used.

Unlike regular employees, contingent workers work through an employment agency or operate as independent contractors.

Unlike regular employees, contingent workers are required to work at least $40$ hours a week.

Unlike contingent workers, regular employees are not covered under the Worker Adjustment and Retraining Notification Act.