Which of the following equations gives the angular momentum of an electron in a stationary orbit?

• A
  $mvr = \frac{2 \pi}{h} \times n$
• B
  $mvr = \frac{nh}{2 \pi}$
• C
  $mvh = n \times \frac{r}{2 \pi}$
• D
  $mv = \left( \frac{h \times r}{2 \pi} \right) n$