Explanation:

- Option 1: 42nd Amendment

This is the correct answer. The Preamble to the Indian Constitution was first amended by the 42nd Amendment, also known as the "Constitution (Forty-second Amendment) Act, 1976". This amendment added the words "Socialist", "Secular", and "Integrity" to the Preamble.

- Option 2: 1st Amendment

This amendment, enacted in 1951, focused on issues related to freedom of speech, land reform, and the validation of certain acts and regulations. It did not amend the Preamble.

- Option 3: 73rd Amendment

This 1992 amendment dealt with the Panchayati Raj institutions and added the Eleventh Schedule to the Constitution. It did not affect the Preamble.

- Option 4: None of the above

Incorrect, as the 42nd Amendment did amend the Preamble.