What is needed to enter/load an encryption key on an AN/PRC-152A radio?

The correct choice is the key fill device, which is specifically designed to load and enter encryption keys into secure communication devices such as the AN/PRC-152A radio. A key fill device is essential for ensuring that the encryption keys are securely transmitted into the radio without risk of exposure to unauthorized users.

This device typically allows for the secure transfer of cryptographic information and is used in various military communications systems to maintain operational security. The AN/PRC-152A radio relies on such devices to manage encryption keys effectively, ensuring that communications are protected.

While other options may seem related to connectivity or secure data transfer, they do not have the specific functionality required for loading encryption keys into the radio. The USB port, for instance, might provide a means for connecting external devices, but it does not ensure the secure or proper loading of cryptographic information. Similarly, a data cable can connect devices, but it lacks the specialized capability of a key fill device, while an encryption module refers to the internal components responsible for processing encrypted information, rather than the mechanism for loading encryption keys.