Entity line

$5.$ The following is a correct DNS resource records $($RR$)$ format of type MX: $(0\mathrm{.}5$ Points$)$

$($

abc.com,

mail.abc.com, MX$,86400)$

$($

abc.com, $123\mathrm{.}15\mathrm{.}25\mathrm{.}11,$ MX$,86400)$

$($

mail.abc.com,

abc.com, MX$,86400)$

All of the above