What is the maximum height of any vehicle that may be operated without a special permit?

Answer: B — 13 feet

In Indiana, the maximum height of any vehicle that may be operated without a special permit is 13 feet. This limit is set to ensure the safety of the vehicle on roads, under bridges, and near other structures where overhead clearance is a concern. Vehicles exceeding this height would require a special permit to operate legally on Indiana roads. Option A is incorrect because 12 feet is lower than the maximum height allowed. Option C is incorrect as it exceeds the maximum height of 13 feet. Option D is also incorrect as 15 feet is higher than the allowed height limit without a special permit.