The contracting officer—

(a) Must apply the evaluation procedures of this subpart to each line item of an offer unless either the offer or the solicitation specifies evaluation on a group basis (see 25.503);

(b) May rely on the offeror's certification of end product origin when evaluating a foreign offer;

(c) Must identify and reject offers of end products that are prohibited in accordance with subpart 25.7; and

(d) When trade agreements are involved, must not use the Buy American statute evaluation factors prescribed in this subpart to provide a preference for one foreign offer over another foreign offer.