In public key encryption, which key is used to decrypt information sent by another individual?

In public key encryption, information sent by one individual is encrypted using the recipient's public key. To decrypt this information, the recipient uses their corresponding private key. The private key is kept secret and is only known to the recipient, ensuring that only they can access and decrypt the information that has been sent to them.

This system relies on the asymmetry of key pairs—each user has a public key that can be shared widely and a private key that is kept confidential. This mechanism enhances security by allowing secure communication over potentially insecure channels. Other given choices involve either the use of keys that are not suitable for decryption in this context or refer to the encryption keys of the sender, which are not applicable to the decryption process by the recipient.