Concept:Panchayati Raj institutions exist in most Indian states, except a few special category states, due to their unique administrative structures.
Explanation:The 73rd Constitutional Amendment Act of 1992 gave constitutional status to Panchayati Raj.
This system is not implemented in the states of Nagaland, Meghalaya, and Mizoram.
These states have their own traditional village governance systems, such as village councils under the Sixth Schedule.
Among the given options, only Mizoram falls under this exception.
West Bengal, Kerala, and Bihar have active Panchayati Raj systems.
Therefore, Mizoram is the state without a Panchayat system.
Answer:Option A: Mizoram