The correct answer to the question is option 3, the 42nd Amendment Act. The word `Secular` was indeed inserted into the Constitution of India through this amendment.

To provide a better understanding of the other options, we can dissect them as follows:

- Option 1: The 44th Amendment Act did not introduce the word `Secular` into the Constitution. This amendment primarily focused on restoring some of the democratic rights that were curtailed during the state of emergency in India.

- Option 2: The 52nd Amendment Act also did not introduce the word `Secular` into the Constitution. This amendment primarily dealt with the anti-defection law and prohibiting defection of elected representatives.

- Option 4: The 34th Amendment Act does not exist. Therefore, it is not a correct answer.

Therefore, Option 3, the 42nd Amendment Act, remains the correct answer as it is the only option that correctly identifies the amendment that introduced the word `Secular` into the Constitution of India.