Which command generates a 2048-bit RSA key pair at ~/.ssh/id_rsa with an empty passphrase?
~/.ssh/id_rsa
ssh-keygen -t rsa -b 2048 -N "" -f ~/.ssh/id_rsa
ssh-keygen -t rsa -b 2048 -N ~/.ssh/id_rsa
ssh-keygen -t rsa -b 2048 -N "" -f ~/.ssh/authorized_keys
ssh -t rsa -b 2048 -N "" ~/.ssh/id_rsa