Final answer:
The Romans sweetened their wine by adding honey, which was a common practice to enhance flavor and sweetness. Mixing wine with water was also regular for dilution, not to make wine sweeter. The correct option is A.
Step-by-step explanation:
The Romans fortified their wine with honey to make it sweeter.
While they also commonly mixed wine with water for dilution, as they believed that consuming undiluted wine was a habit of barbarians or alcoholics, the addition of honey was meant to enhance the flavor of the wine and add sweetness.
This practice of sweetening wine with honey is known historically and was part of the culinary habits of the Romans.
Hence, Option A is correct.