The correct option is Modification of the Anti-defection law..
Explanation
The Constitution (Ninety-first Amendment) Act, 2003, was enacted to strengthen the Anti-Defection Law (Tenth Schedule) and to place a ceiling on the size of the Council of Ministers to prevent jumbo cabinets.
Detailed Analysis:
- Modification of Anti-Defection Law: The 91st Amendment modified the Tenth Schedule by omitting the provision that protected a "split" in a political party. Previously, if one-third of the members of a legislature party split, they were not disqualified. This exception was removed, and now only a "merger" (involving at least two-thirds of the members) is protected from disqualification.
- Limiting the Size of the Council of Ministers: The Amendment added Clause (1A) to Article 75 and Article 164. It mandates that the total number of Ministers, including the Prime Minister (at the Centre) or the Chief Minister (in a State), shall not exceed 15% of the total number of members of the Lok Sabha or the Legislative Assembly of that State, respectively.
- Other Options:
- Introduction of GST: This was achieved through the 101st Constitutional Amendment Act, 2016.
- Right to Information: This is a statutory right established by the Right to Information Act, 2005, not a Constitutional Amendment.
- Formation of Telangana: This was executed through the Andhra Pradesh Reorganisation Act, 2014, under Article 3 of the Constitution, which does not require a Constitutional Amendment under Article 368.
Key Takeaway:
The 91st Amendment (2003) is pivotal for capping the Council of Ministers at 15% of the Lower House strength and removing the "split" exception from the Anti-Defection Law.