Which of the following is an example of a nested process?

A candidate's intent to graduate is checked for financial holds by the Bursar and for degree requirements by Advising before the diploma mill prints their sheepskin.

A customer service representative verifies a caller's account information.

A stockbroker calls a client and advises her to sell silver short.

At the start of the new semester, a student first pays tuition and then goes to the bookstore.