Ruprect needs to add a third$-$party repository to the Debian Package Manager in order to install the correct driver for a Fibre Channel HBA. The HBA manufacturer has supplied him with a file that contains the necessary repository location. To which directory can Ruprect copy this file to ensure that it will be used the next time he runs an apt update command?

a$./$etc$/$apt

b$./$etc$/$apt$/$sources$.$list.d

c$./$etc$/$dpm

d$./$etc$/$dpm$/$repolist