Which type of container is used to ship radioactive materials by air?

The correct answer is based on the regulations regarding the transport of radioactive materials by air. Type C containers are specifically designed to handle the transport of radioactive materials in a manner that meets the stringent safety requirements laid out by organizations such as the International Atomic Energy Agency (IAEA) and other relevant authorities.

Type C containers are constructed to withstand considerable physical and thermal stress during air transport, including the forces experienced during a potential aircraft accident. They are capable of containing large quantities of radioactive material while ensuring that radiation levels outside the container remain within safe limits.

In contrast, Type A and Type B containers are designed for other purposes. Type A containers are intended for lower levels of radioactivity and are not suitable for the robust conditions faced in air transport of higher activity materials. Type B containers, while used for the transport of high-activity materials, are predominantly designed for transportation by road or rail, as they are built to handle severe accidents on those modes rather than the unique challenges of air transport. Type D does not exist in the context of radioactive material transport, making Type C the appropriate choice for air shipping scenarios.