The Assertion (A) is correct, as Lord Wellesley’s Subsidiary Alliance system weakened the Indian Princely States by placing them under British protection while limiting their autonomy. It effectively reduced their ability to govern independently.
The Reason (R) is also correct, as the system caused Indian rulers to lose their military autonomy by forcing them to maintain British troops in their courts and pay for their upkeep. This led to the further consolidation of British control over India. Thus, Reason (R) correctly explains the consequences of the Subsidiary Alliance system introduced in the context of Assertion (A).