The 'tripartite struggle' (8th-10th centuries) for control over Kannauj was fought between the:

The "tripartite struggle" was a long conflict between three powerful dynasties, the Palas, the Gurjara-Pratiharas and the Rashtrakutas, for control over Kannauj, in the 8th-10th centuries.

Why Kannauj was important:

• After Harsha made it his capital in the 7th century, Kannauj became the most important political centre of northern India.
• It was located in the fertile Ganga-Yamuna Doab, which was rich in agriculture.
• It was an important centre of trade and communication.
• Controlling Kannauj gave prestige and the claim to be the paramount power of northern India.

NCERT notes that rulers belonging to the Gurjara-Pratihara, Rashtrakuta and Pala dynasties fought for control over Kannauj, and historians often describe it as the "tripartite struggle" because there were three "parties" in this long-drawn conflict.

The three dynasties:

• "Gurjara-Pratiharas": ruled western India (Rajasthan, Gujarat, Malwa), and later Kannauj.
• "Palas": ruled eastern India (Bengal and Bihar).
• "Rashtrakutas": ruled the Deccan.

Course of the struggle:

• Vatsaraja (Pratihara) and Dharmapala (Pala) fought for Kannauj; the Rashtrakuta king Dhruva invaded the north and defeated both.
• Dharmapala placed his nominee Chakrayudha on the throne of Kannauj.
• Nagabhata II (Pratihara) defeated Chakrayudha and captured Kannauj, but was then defeated by the Rashtrakuta king Govinda III.
• Mihira Bhoja (Pratihara) finally established the Pratihara control over Kannauj in the 9th century.
• The Rashtrakutas, though they won many battles in the north, could not hold territory there for long, because it was far from their base in the Deccan.

Results:

• The struggle lasted for about 200 years and weakened all three dynasties.
• It made northern India vulnerable to later invasions from the north-west.
• The Gurjara-Pratiharas ultimately held Kannauj until the 11th century.

Why not the other options?

• ✗The Cholas, Pallavas and Chalukyas were southern dynasties.
• ✗The Chandelas, Paramaras and Chalukyas (Solankis) were later Rajput dynasties.
• ✗The Gahadavalas, Chauhans and Senas ruled in the 11th-12th centuries.