Answer : 4. "11 + one Chief Minister "
Explanation :

1. According to the provisions of the 91 Constitutional Amendment Act 2003, the maximum number of Council of Ministers cannot exceed 15% of the membership of the House, hence in Rajasthan, it can be a maximum of 30 including the Chief Minister.

2. The minimum number of Rajasthan Council of Ministers can be 11 + 1 Chief Minister.