The first Constitutional Amendment was passed in 1951. The main object was

The first Constitutional Amendment Act of 1951 introduced several important changes to the Constitution of India. It aimed to provide constitutional validity to land reform laws and protect them from legal challenges. This objective was achieved by adding Article 31A, which provided for the saving of laws giving effect to certain Directive Principles of State Policy related to agrarian reforms.

Additionally, Article 31B was inserted to provide immunity to laws included in the Ninth Schedule of the Constitution from judicial review. The Ninth Schedule was created to protect land reform laws and other socio-economic legislations from being invalidated by the courts on the grounds of violating fundamental rights.

Therefore, the correct answer is:
B. To add Articles 31A and 31B and Schedule 9