Given the following passage  "Oklahoma City is protected by the Oklahoma City Fire Department (OKCFD), which employs 1015 paid, professional firefighters. The current Chief of Department is G. Keith Bryant, the department is also commanded by three Deputy Chiefs, who – along with the department chief – oversee the Operational Services, Prevention Services, and Support Services bureaus. The OKCFD currently operates out of 37 fire stations, located throughout the city in six battalions. The OKCFD also operates a fire apparatus fleet of 36 engines (including 30 paramedic engines), 13 ladders, 16 brush patrol units, six water tankers, two hazardous materials units, one Technical Rescue Unit, one Air Supply Unit, six Arson Investigation Units, and one Rehabilitation Unit. Each engine is staffed with a driver, an officer, and one to two firefighters, while each ladder company is staffed with a driver, an officer, and one firefighter. Minimum staffing per shift is 213 personnel. The Oklahoma City Fire Department responds to over 70,000 emergency calls annually.",  answer the following question. Note that the answer is present within the text.  Question: Does the fire apparatus fleet have a lower number of Air Supply Units or Arson Investigation Units?
Answer:
Air Supply Unit