Final answer:
The character tasked with rounding up the mares of Diomedes is Hercules, as part of his Twelve Labours. This labor underscores his renowned strength and heroism in Greek mythology.
Step-by-step explanation:
The question asks who was tasked with the goal to round up the mares of Diomedes. The answer is B) Hercules. This challenge was one of the tasks assigned to Hercules as part of the Twelve Labours set by King Eurystheus. It is one of the numerous myths surrounding Hercules, who is one of Greece’s most celebrated heroes. The mares of Diomedes were known to be wild and fierce, and bringing them back proved to be a remarkable feat for Hercules. Unlike Perseus, who is more famously known for defeating Medusa, Hercules's extensive labors included capturing the mares. This task is indicative of his strength and tenacity as a hero in Greek mythology.