Explanation:

- Option 1: Dhruva was a ruler of the Rashtrakuta dynasty but not its founder. He ruled after Dhantidurga and expanded the kingdom.

- Option 2: Dhantidurga is indeed the founder of the Rashtrakuta dynasty. He is credited with establishing their power in the Deccan region.

- Option 3: Govinda III was a prominent Rashtrakuta ruler known for his military conquests. However, he wasn't the founder of the dynasty.

- Option 4: Amoghavarsha was a celebrated Rashtrakuta king, renowned for his patronage of arts and literature. He came later, after Dhantidurga.