The Supreme Court Ruling Which Requires Management to Bargain Over

The Supreme Court ruling which requires management to bargain over the decision to unilaterally replace bargaining unit members with subcontractors to do essentially the same work under similar conditions is the:

A) ​Americans with Disabilities Act.
B) ​Reasonable Accommodations Ruling.
C) ​Fibreboard Ruling.
D) ​Fair Job Security Ruling.
E) ​Seniority Preservation Act.