Explanation:

- Option 1: B.R. Ambedkar

He was the Chairman of the Drafting Committee of the Indian Constitution, but he did not propose the Preamble.

- Option 2: Mahatma Gandhi

Gandhi was a key leader in the freedom struggle, but he was not a member of the Constituent Assembly and did not propose the Preamble.

- Option 3: B.N. Rao

He was the Constitutional Advisor, who helped with the drafting, but he did not move the Preamble.

- Option 4: Jawaharlal Nehru

? Nehru actually proposed the “Objectives Resolution” in the Constituent Assembly on December 13, 1946, which later formed the basis for the Preamble.