Final answer:
The RSA algorithm is suitable for both digital signature and encryption, unlike MD5, SHA-1, and AES, which cannot be used for both.
Step-by-step explanation:
The correct answer to which algorithm is suitable for both digital signature and encryption is C). RSA. The MD5 and SHA-1 algorithms are hashing functions, which means they take input and produce a fixed-size hash value or digest. These hash functions don't support encryption or decryption and thus are not used for these purposes. On the other hand, the Advanced Encryption Standard (AES) is an encryption algorithm, widely used for securing data, but it does not provide digital signature capabilities.
RSA (Rivest-Shamir-Adleman) is an asymmetric cryptographic algorithm that can be used for both encrypting messages and creating digital signatures. In RSA, each user has a pair of keys: a public key, which can be shared with anyone, and a private key, which must be kept secret. Digital signatures are created by generating a hash of the message and then encrypting the hash with the signer's private key. To encrypt a message, RSA uses the recipient's public key. To decrypt it, the private key is required.