Which of the following is not an "authorized emergency vehicle" in accordance with the Transportation Code?

a. police vehicles
b. private vehicles operated by volunteer fire fighters while answering a fire alarm
c. a vehicle operated by an employee of the blood bank transporting the daily supply of fresh blood to a local hospital under normal circumstances.
d. the operator of a vehicle owned by an eye bank while making an emergency delivery of eye tissue to the airport.
e. none of the above