At the Union level in India, who has the authority to amend the Constitution of India?

Introduction / Context:
The Constitution of India is a supreme legal document that can be amended only through a special procedure. Understanding who has the formal authority to amend it is a basic but very important concept in Indian polity. Many objective questions test this directly, since it reflects the distribution of powers between different organs and institutions of the state.

Given Data / Assumptions:
- The question asks who has the authority to amend the Constitution at the Union level.
- The options include various bodies and offices such as a ministry, the Prime Minister Office, Parliament, a regulatory body and the Supreme Court.
- We assume the question refers to the formal law making power, not to interpretation or judicial review.

Concept / Approach:
Article 368 of the Constitution of India lays down the procedure for amendment. It specifies that Parliament may amend the Constitution by passing a Constitution Amendment Bill with a special majority, and in certain cases, ratification by at least half of the state legislatures is also required. However, the institution that initiates and passes the amendment at the Union level is Parliament, not the executive or the judiciary.

Step-by-Step Solution:
Step 1: Recall Article 368 and its statement that Parliament may amend the Constitution by way of addition, variation or repeal of any provision. Step 2: Identify Parliament as the supreme law making body at the Union level, consisting of Lok Sabha and Rajya Sabha. Step 3: Note that the Prime Minister Office and ministries are part of the executive, which can propose changes but does not itself pass amendments. Step 4: Recognise that the Supreme Court interprets the Constitution and can strike down unconstitutional amendments, but it does not amend the document formally. Step 5: Select Parliament as the institution with constitutional authority to amend the Constitution.

Verification / Alternative check:
Standard Indian polity textbooks and the text of Article 368 make it explicit that Parliament may amend the Constitution using the procedure prescribed. Court judgements such as those on the basic structure doctrine discuss the limits of this power but still clearly state that the power itself belongs to Parliament. No provision gives amendment power to the executive or regulatory bodies, confirming that Parliament is the correct answer.

Why Other Options Are Wrong:
Ministry of Defence: A ministry executes defence policy but does not possess constitutional amendment powers.
Prime Minister Office: The Prime Minister leads the government but has no independent authority to amend the Constitution without parliamentary procedure.
Securities and Exchange Board of India: This is a statutory regulator for securities markets and has no role in constitutional amendments.
Supreme Court of India: It can review and interpret amendments but cannot initiate or pass them as formal law in place of Parliament.

Common Pitfalls:
Some candidates become confused by the influence of the executive in the legislative process and mistakenly think that the Prime Minister Office can directly amend the Constitution. Others overestimate the role of the Supreme Court in constitutional change, thinking that interpreting or striking down provisions is the same as amending them. Remembering that amendment is a legislative function, carried out through a special parliamentary procedure, helps avoid these misunderstandings.

Final Answer:
At the Union level, the authority to amend the Constitution of India lies with the Parliament following the procedure laid down in Article 368.