The correct answer is option 4, The Government of India Act, 1935. The Government of India Act, 1935 was a significant piece of legislation that played a crucial role in shaping the Indian Constitution. This act introduced several important provisions that influenced the drafting of the constitution. It provided for the establishment of a federal structure, which was later adopted in the Indian Constitution. The act also included provisions related to fundamental rights, the power of the federal legislature, and the division of powers between the center and the provinces, all of which were reflected in the Indian Constitution. While the British Constitution, US Constitution, and Irish Constitution may have served as sources of inspiration for certain aspects of the Indian Constitution, it was the Government of India Act, 1935 that had the most profound influence on its framing.