Which command, available with all MTAs, is used to list the contents of the MTA’s mail queue?

Which command, available with all MTAs, is used to list the contents of the MTA’s mail queue? (Specify ONLY the
command without any path or parameters.)

A.
mailq, /usr/bin/mailq, sendmail -bp, /usr/sbin/sendmail – bp, /usr/lib/sendmail -bp