Which of the below mentioned options is a possible reason for rejection?

Explanations:

The error “Host key not found” typically occurs when the user has not connected to the EC2 instance before, or when there is a mismatch between the known host key and the instance’s SSH key. Providing the wrong username can lead to a host key mismatch.

If the CPU of the instance is heavily loaded, it may cause performance issues, but it will not directly lead to a “Host key not found” error. The error is more related to SSH key mismatches.

A misconfigured security group would prevent SSH access entirely, resulting in a timeout or connection failure. It wouldn’t cause a “Host key not found” error, which is related to SSH key verification.

The “Host key not found” error is related to the SSH key verification process, not the access key. The access key is used for API interactions, not SSH. Therefore, an incorrect access key wouldn’t cause this error.