The National Judicial Appointments Commission (NJAC) has been declared…

Under India's basic-structure doctrine (Kesavananda Bharati v. State of Kerala, 1973), a Constitutional amendment can be tested against, and struck down for violating, a feature the Constitution treats as fundamental to its identity — such as an independent judiciary. Under Article 141, law declared by the Supreme Court binds every court in India regardless of the bench's size; separately, Article 145(3) requires a Constitution Bench of at least five judges whenever a case involves a substantial question of interpreting the Constitution. The NJAC case was exactly such a substantial-interpretation matter, and it was resolved by such a Constitution Bench, whose ruling — under Article 141 — is what finally and nationally settled the question.

In Supreme Court Advocates-on-Record Association v. Union of India (2015) — commonly called the Fourth Judges Case — a five-judge Constitution Bench of the Supreme Court examined the 99th Constitutional Amendment Act, 2014 and the accompanying National Judicial Appointments Commission Act, 2014, which replaced the collegium system with a commission in which the Union Law Minister and two 'eminent persons' would sit alongside judges in appointing and transferring judges. By a 4:1 majority, the Bench held that this composition diluted the primacy of the judiciary in its own appointments and impaired judicial independence, a part of the basic structure. It therefore struck down both the 99th Amendment and the NJAC Act, 2014, and restored the pre-existing collegium system.

Checking the near-miss options against this same case:

• The High Court: an Article 226 ruling by a High Court sets a binding precedent only for the subordinate courts within that High Court's own territorial jurisdiction, and does not bind other High Courts or settle a Constitutional question for the country as a whole; this particular ruling was delivered directly by a Supreme Court Constitution Bench, not by any High Court.

• The High Court and the Supreme Court both: no High Court sat with the Supreme Court on this matter — the ruling came from a Supreme Court Constitution Bench alone, without any High Court's involvement.

• The President of India: the President's role in this sequence was to give assent to the 99th Amendment Bill after Parliament passed it in 2014; assent is a legislative formality, not a judicial finding, and the President has no power to later adjudicate the validity of a law they signed.

So the correct answer is the Supreme Court of India, which struck down the NJAC in its 2015 Fourth Judges Case ruling.