Explanation:

- Option 1: Parliament of India

- The Parliament was established after the adoption of the Constitution.

- It did not have a role in the adoption process.

- Option 2: Constituent Assembly

- ? Correct Answer

- The Constituent Assembly was set up specifically to draft and adopt the Constitution.

- It was responsible for debating and finalizing the document.

- Option 3: Governor General

- The Governor General had limited powers in this context.

- He had no direct role in adopting the Constitution.

- Option 4: British Parliament

- The British Parliament did not adopt the Indian Constitution.

- It only facilitated the process through the Indian Independence Act.