Final answer:
Rome fought Carthage in the Punic Wars for control of the Mediterranean, resulting in Rome's dominance over the region after their victory.
Step-by-step explanation:
After its initial conquests of the Italian peninsula, Rome encountered a formidable rival across the Mediterranean Sea: Carthage. These two great powers fought for supremacy in a series of conflicts known as the Punic Wars. The struggle culminated in Rome's victory over Carthage, granting Rome control over much of the Mediterranean. The answer to the student's question is d. the Mediterranean. During the First Punic War, Rome innovatively turned naval battles to their advantage by boarding enemy ships and transforming the combat into a type of warfare where they excelled. As time progressed, Rome's military campaigns extended beyond the Mediterranean, bringing even the Hellenistic kingdoms into their sphere of influence.