The Gandhi-Irwin pact was an agreement signed between Mohandas Gandhi and Lord Irwin in March 1931. It aimed to resolve the issues and tensions between the Indian National Congress and the British government.

Option 1: Immediate release of all political prisoners of the Civil Disobedience Movement. This provision was indeed part of the Gandhi-Irwin pact. It called for the release of all political prisoners who had been arrested during the Civil Disobedience Movement.

Option 2: Clause 2 of the March 1931 pact defined ‘reservations and safeguards’ to cover financial credit of India. This provision was also included in the Gandhi-Irwin pact. It sought to address the issue of reservations and safeguards for the financial credit of India.

Option 3: The return of confiscated land already sold to third parties. This provision was NOT part of the Gandhi-Irwin pact. The agreement did not address the issue of returning confiscated land.

Option 4: Reservation of 18 per cent seats for Depressed classes. This is the correct answer. The provision of reserving 18 per cent of seats for the Depressed classes was NOT part of the Gandhi-Irwin pact.

Therefore, the correct answer is option 4, as it does