Which one of the followings has maximum number of atoms $?$

$[2020]$

$($a$)1g$ of $Mg(s)[$Atomic mass of $Mg=24]$

$($b$)1g$ of $O_2(g)[$Atomic mass of $O=16]$

$($c$)1g$ of $Li(s)[$Atomic mass of $Li=7]$

$($d$)1g$ of $Ag(s)[$Atomic mass of $Ag=108$