When two different keys encrypt a plaintext message into the same
ciphertext, this situation is known as:

A.
Cryptanalysis.

B.
Public key cryptography.

C.
Hashing.

D.
Key clustering.

Explanation:
The correct answer is “Key clustering”
Answer “Public key cryptography” describes a type of cryptographic
system using a public and a private key; answer Cryptanalysis is the art/science
of breaking ciphers; answer Hashing is the conversion of a message of variable
length into a fixed-length message digest.