If the $p-n$ junction diode is unbiased,

• A
  $n$-type side has lower potential than $p$-type side.
• B
  $n$-type side has same potential as $p$-type side.
• C
  An electric field is established at the junction such that $n$-side is at positive voltage relative to $p$-side.
• D
  The potential across the junction is such that $p$-side is at positive voltage relative to $n$-side.