The ssh-add program ran for user maria, but his RSA identity files were not added, what could be the reason for this?

The ssh-add program ran for user maria, but his RSA identity files were not added, what could be the reason for this?

• The file /home/maria/.ssh/id_rsa had read permissions for no other user except Maria
• The file /home/maria/.ssh/id_rsa has read permissions only for Maria
• The file /home/maria/.ssh/id_rsa had read and write permissions only for Maria
• The file /home/maria/.ssh/id_rsa has read permissions for users other than Maria