Case Corp. is incorporated in State A.Under the Revised Model Business corporation act, which of the following activities engaged in by Case requires that Case obtain a certificate of authority to do business in State B?

a.

Maintaining an office in State B to conduct intrastate business.

b.

Hiring employees who are residents of State B.

c.

Collecting corporate debts in State B.

d.

Maintaining bank accounts in State B.