Step 1: Understand the purpose of the 91st Amendment.
Passed in 2003, it aimed to stop governments from having huge ministries, which waste public money and weaken efficiency.
Step 2: Find the inserted rule.
The amendment added Article 75(1A), which caps the size of the Union Council of Ministers.
Step 3: Recall the exact limit.
The total number of ministers, including the Prime Minister, must not be more than 15% of the strength of the Lok Sabha.
Step 4: Note the matching state rule.
Article 164(1A) sets the same 15% limit for state ministries, with a minimum of 12 ministers.
Step 5: Conclude.
The figure asked for is 15% of the Lok Sabha.
Answer: 15% of the total number of members in Lok Sabha (Option 4).