Adviser of Chandragupta Maurya was Kautilya, also known as Chanakya. He was a well-known political strategist and philosopher in ancient India.

Background:
Kautilya was born in 4th century BCE in a Brahmin family in the kingdom of Magadha. He was a teacher, philosopher, and a statesman. He is known for his famous book, Arthashastra, which is a comprehensive treatise on statecraft, military strategy, economics, and politics.

Role as adviser:
Kautilya played a crucial role in the rise of Chandragupta Maurya to power. He saw the potential in Chandragupta and trained him in the art of war and statecraft. Kautilya also helped Chandragupta form alliances with other kingdoms and overthrow the ruling Nanda dynasty.

After Chandragupta became the emperor, Kautilya served as his chief adviser and helped him in the administration of the empire. He played a key role in the expansion of the Mauryan empire and the establishment of its capital in Pataliputra.

Kautilya's advice to Chandragupta:
Kautilya's advice to Chandragupta was based on the principles of realpolitik, which emphasized the use of force, diplomacy, and cunning to achieve political goals. He advised Chandragupta on various matters, including:

1. Economic policies: Kautilya advised Chandragupta on taxation, trade, and agriculture policies to strengthen the economy of the empire.

2. Foreign relations: Kautilya helped Chandragupta form alliances with other kingdoms and also advised him on how to deal with hostile neighbors.

3. Military strategy: Kautilya trained Chandragupta in the art of war and advised him on military campaigns and tactics.

4. Administration: Kautilya helped Chandragupta in the administration of the empire and advised him on how to maintain law and order.

Conclusion:
Kautilya's role as the adviser of Chandragupta Maurya was instrumental in the rise and expansion of the Mauryan empire. His principles of realpolitik and his book, Arthashastra, continue to be studied and admired by scholars and politicians even today.

Kautilya Chankaya was the adviser of Chandragupta Maurya, so the correct answer is option 'C'.