Final answer:
The appropriate placards required on an aircraft operating under CARS are specified in CAR 625, Appendix H, which contains all the necessary guidelines for placarding to meet safety and compliance standards.
Step-by-step explanation:
The appropriate placards required on an aircraft operating under the Canadian Aviation Regulations (CARS) are specified in CAR 625, Appendix H. These regulations provide comprehensive guidelines on the required placards and markings that must be displayed on an aircraft to ensure safety and to comply with the legal requirements. The placards include important safety information, operating limits, and instructions which are critical for the safe operation of the aircraft. Contradictory options like the maintenance manual or Aircraft type certificate data sheet may provide detailed information about the aircraft itself, but the specifics of placarding requirements under Canadian regulations are contained within CARS.