Final answer:
The drug affected by Mandatory Allowable Cost (MAC) is a prescription drug. The Medicare Prescription Drug and Modernization Act of 2003 introduced a prescription drug discount card program to assist Social Security recipients in saving on prescription drugs.
Step-by-step explanation:
The drug that is affected by Mandatory Allowable Cost (MAC) is a prescription drug. Medicare's Prescription Drug and Modernization Act of 2003 introduced two types of assistance programs, one being a prescription drug discount card program. This program helps Social Security recipients save around 15% to 25% annually on prescription drugs.