As when a hash algorithm is applied on a message , it produces a message digest.
The other answers are incorrect because :
A digital signature is a hash value that has been encrypted with a sender’s private key. A ciphertext is a message that appears to be unreadable.
A plaintext is a readable data. Reference : Shon Harris , AIO v3 , Chapter-8 : Cryptography , Page : 593-594 , 640 , 648