What is a system of a secure key pair consisting of a private key for

What is a system of a secure key pair consisting of a private key for creating a digital signature and a public key to verify the digital signature, known as:

Asymmetric crypto system
Secure system
Symmetric crypto system
Digital signature certificate
This question was previously asked in
UPSC CISF-AC-EXE – 2023
The correct answer is A) Asymmetric crypto system.
A system using a pair of mathematically related keys, one private and one public, where the private key is used for operations like creating a digital signature and the public key is used for verification, is known as an asymmetric crypto system. This is also commonly referred to as public-key cryptography.
In asymmetric cryptography, the public key can be freely distributed, while the private key must be kept secret by its owner. For digital signatures, the sender uses their private key to sign data. The recipient uses the sender’s public key to verify that the signature is valid and was created by the owner of the corresponding private key. Symmetric crypto systems use the same key for both encryption/decryption or signing/verification, which is not the case described here. A digital signature certificate is a digital document that uses asymmetric cryptography to link a public key to an identity, but it is not the crypto system itself.