dpkg-reconfigureの「-plow」オプションは何をしますか？

~からあなたがリンクしたマンページdpkg-reconfigure:

-血値、- 優先順位=値
   表示される質問の最も低い優先順位を指定します。 dpkgの再構成
   デフォルトの優先順位に関係なく、通常は優先順位の低い問題が表示されます。バラより
   デブカンファレンス（7）リストを作成してください。

そしてからman 7 debconf:

Another  nice feature of debconf is that the questions it asks you are prioritized. If you
don't want to be bothered about every little thing, you can set up debconf to only ask you
the most important questions.  On the other hand, if you are a control freak, you can make
it show you  all  questions.  Each  question  has  a  priority.  In  increasing  order  of
importance:

low    Very  trivial  questions  that have defaults that will work in the vast majority of
       cases.

medium Normal questions that have reasonable defaults.

high   Questions that don't have a reasonable default.

critical
       Questions that you really, really need to see (or else).

Only questions with a priority equal to or greater than the priority you  choose  will  be
shown  to  you. You can set the priority value by reconfiguring debconf, or temporarily by
passing  --priority=  followed  by  the  value  to  the  dpkg-reconfigure(8)   and   dpkg-
preconfigure(8) commands, or by setting the DEBIAN_PRIORITY environment variable.

したがって、-plow他の場所に設定されているデフォルト値に関係なく、すべての問題が表示されます。おそらくこれはあなたが望むものです（通常私私が走ったら欲しいdpkg-reconfigure）。