Correct Option
Only the National Commission for Backward Classes (NCBC) among the given options is a constitutional body.
The NCBC was granted constitutional status through the 102nd Constitutional Amendment Act, 2018. This amendment inserted Article 338B into the Constitution, thereby establishing the NCBC as a constitutional body with specific powers and functions.
Incorrect Options
The other three organizations are not constitutional bodies:
The National Human Rights Commission (NHRC) is a statutory body. It was established under the Protection of Human Rights Act, 1993, which is an Act of Parliament.
The National Law Commission is an executive body. It is constituted by the Government of India through an executive order from time to time to advise on legal reforms, and is neither a constitutional nor a statutory body.
The National Consumer Disputes Redressal Commission (NCDRC) is a statutory body. It was established under the Consumer Protection Act, 1986, which is an Act of Parliament.
Since only one body (NCBC) in the list holds constitutional status, options (b), (c), and (d) are incorrect.