Sas no. 144 amends au-c 501 to require the auditor to perform which of the following steps with respect to a management's specialist: A. obtain an understanding of the work of the specialist B. negotiate the terms of the agreement to engage management's specialist C. make recommendations to management about changes in scope that should be negotiated into the engagement letter of management's specialist D. override management by deciding to engage an auditor's specialist in lieu of management hiring its own specialist