The correct answer is option 2: by the Parliament alone. The Indian Constitution provides for amendments to be made primarily by the Parliament without requiring the involvement of the State Legislatures. The process for amending the Constitution is outlined in Article 368, and it states that amendments can be initiated only by the Parliament. The amendment must be passed by both houses of Parliament - the Lok Sabha (House of the People) and the Rajya Sabha (Council of States) - with a special majority, which means two-thirds of the members present and voting. After the Parliament approves the amendment, it is sent to the President for assent. It is important to note that some specific amendments may require the ratification of the State Legislatures, but this is not applicable to the majority of provisions of the Indian Constitution.