Explanation:

Both pair 2&3 are incorrect.

First Amendment Act, 1951 provided for the saving of laws providing for acquisition of estates, etc.

• Added Ninth Schedule to protect the land reforms and other laws included in it from the judicial review. After Article 31, Articles 31A and 31B were inserted.
• Added three more grounds of restrictions on freedom of speech and expression: public order, friendly relations with foreign states and incitement to an offence. Also, it made the restrictions ‘reasonable’ and thus, justiciable in nature.
• Provided that state trading and nationalisation of any trade or business by the state is not to be invalid on the ground of violation of the right to trade or business.

Twenty Fourth Amendment Act, 1971 affirmed the power of Parliament to amend any part of the Constitution including fundamental rights by amending Article 13 and 368.

• Made it compulsory for the President to give his assent to a Constitutional Amendment Bill. Hence, pair 2 is not correctly matched.

The Sixty-First Amendment Act, 1989 reduced the voting age from 21 years to 18 years for the Lok Sabha and state legislative assembly elections.

The 10th Schedule of the Indian Constitution contains Provisions relating to disqualification on the ground of defection.

• It was included under the 52nd Constitution Amendment Act, also called Anti Defection Act (1985).