An Effective Method to Minimize the Possibility That a Prior

An effective method to minimize the possibility that a prior employer of a prospective employee will refuse to provide a reference on the grounds that a reference can give rise to defamation liability is

A) to require all prospective employees to sign a document releasing former employers from liability for providing references, and providing a copy of the release to prior employers from whom references are sought.
B) conduct reference checks secretly.
C) have the references checked by an unrelated third party.
D) check only references that are adequately insured against defamation.