The correct answer is option 'B', Mihir Bhoja.

Explanation:
Mihir Bhoja was a ruler from the Gurjara-Pratihara dynasty, which was one of the most powerful dynasties in northern India during the medieval period. He reigned over the kingdom of Kannauj from 836 to 885 CE. Mihir Bhoja is known for his military campaigns, patronage of arts and literature, and his adoption of the title Adivarah.

Adoption of the Title Adivarah:
Mihir Bhoja adopted the title of Adivarah, which means "the first among warriors". This title signifies his prowess as a warrior and his position as the paramount ruler of his kingdom. By adopting this title, he asserted his authority and established himself as a strong and capable ruler.

Military Campaigns and Expansion:
Mihir Bhoja was known for his military campaigns and his efforts to expand his kingdom. He conducted several successful military expeditions against neighboring kingdoms and territories. His conquests included regions such as Malwa, Gujarat, Rajasthan, and parts of present-day Uttar Pradesh. Through his military campaigns, he strengthened his kingdom and established his dominance in northern India.

Patronage of Arts and Literature:
Mihir Bhoja was not only a skilled warrior but also a patron of arts and literature. He was known for his love for learning and his patronage of scholars, poets, and artists. His court was a center of culture and intellectual pursuits. Many renowned scholars and poets were associated with his court and produced notable works during his reign.

Legacy:
Mihir Bhoja's reign marked a period of prosperity and cultural development in the Kannauj kingdom. His military achievements, patronage of arts, and adoption of the title Adivarah showcased his authority and contributed to the prestige of his dynasty. Mihir Bhoja's legacy as a powerful ruler and patron of arts continues to be remembered in Indian history.

In conclusion, Mihir Bhoja, ruler of the Gurjara-Pratihara dynasty, adopted the title of Adivarah to assert his authority as the paramount ruler and showcase his prowess as a warrior. His military campaigns, patronage of arts, and adoption of this title contributed to his legacy as a powerful ruler in Indian history.