Answer: Signature
Explanation:
The CA create a particular signature for calculating the hash code by using the proper hash function. the basic function of the hash function is to map the variable length information into the fixed length data value which is known as hash code.
Then, the CA encrypted the hash code by the CA private key. MD5 and SHA are the example of the hash code. Signature basically covers all the other fields and included the algorithm of signature identifier.
The CA basically attached the signature into the unsigned certificate for creating the signed certificate and then return to the client.
