Which type of cryptographic algorithm takes an input string of any length, and returns a string of any requested variable length?

The correct solution is "Sponge ".

Explanation:

The method of transforming data into unreadable text is synonymous with cryptography, as well as vice-versa.The sponge configuration throughout cryptography seems to be a method of thought, based on a specific-length possible combination as well as a formatting law, which constructs a mechanism connecting variable-length information through variable-length release.

True i belive sorry if i am wrong