Final answer:
The medical abbreviation for "before meals" is ac, which derives from the Latin phrase "ante cibum." It's used to instruct a patient to take medication when the stomach is empty, affecting the drug's effectiveness.
Step-by-step explanation:
The medical abbreviation for "before meals" is D: ac. When a physician prescribes medication, it's essential to know when to take each dose in relation to meals. ac stems from the Latin phrase "ante cibum" which translates to "before meals". This instruction is typically used to ensure that a patient's stomach is empty, affecting the absorption or effectiveness of the medication. Other abbreviations related to medication timing include pc (post cibum, or "after meals") and NPO (nil per os, or "nothing by mouth"). Understanding these abbreviations is crucial for proper medication administration and adherence to medical instructions.