In Which of the Following Cases Is a Successor Employer

In which of the following cases is a successor employer most likely to inherit the predecessor's contractual duty to arbitrate?

A) The successor employer does not accept the existing bargaining unit and the union.
B) There is "substantial continuity" between the old and the new companies.
C) The existing union and the successor employer enter into a new collective bargaining agreement.
D) The successor employer has a good-faith reasonable doubt whether the employees support the incumbent union.