What are information risks that cryptography cannot address? $($Choose all that apply.$)$

Question $5$ Answer

a$.$

Display of data to humans, or output of data as device commands in control systems, needs to be in an unencrypted form to be usable.

b$.$

Even cryptographic support for nonrepudiation cannot prove that a recipient $($authorized or not$)$ actually read and understood or made use of the contents of a protected file or message; it can only prove that they accessed it$.$

c$.$

Cryptography cannot be used to reduce risks to information availability.

d$.$

Users with legitimate access to a variety of information at one level of classification, when decrypted for use, may be able to infer the existence or value of information at higher levels of classification.