Option c is the correct answer. Skandagupta defeated the Hunas, who were a nomadic tribe from Central Asia that invaded India in the 5th century CE. The Hunas were led by Toramana and his son Mihirakula, who were ruthless and oppressive rulers. They destroyed many temples, monasteries, and cities in northern India. He restored peace and prosperity in his kingdom and protected the culture and civilization of India. He is praised for his heroism and courage in the Bhitari Pillar Inscription, which was composed by his court poet Harishena. The inscription also mentions his other achievements, such as his victory over the Vanga kings, his generosity towards his subjects, and his devotion to his father.