Step 1: Understanding the Question
The question asks for the constitutional limit on the size of the Union Council of Ministers (which includes the Prime Minister).
Step 2: Constitutional Provision
Originally, there was no limit on the size of the Council of Ministers, which often led to very large ("jumbo") cabinets. To curb this, the 91st Constitutional Amendment Act of 2003 was passed.
This amendment inserted Clause (1A) into Article 75 of the Constitution, which states:
"The total number of Ministers, including the Prime Minister, in the Council of Ministers shall not exceed fifteen per cent. of the total number of members of the House of the People [Lok Sabha]."
A similar provision was made for State governments, limiting their Council of Ministers to 15% of the strength of the Legislative Assembly (with a minimum of 12 ministers).
Step 3: Evaluating the Options
Based on Article 75(1A), the maximum size of the Union Council of Ministers is 15 percent of the total strength of the Lok Sabha.
Step 4: Final Answer
The maximum number of members is 15 percent of the total number of members of Loksabha. Therefore, option (B) is the correct answer.