Which of the following statements is true?

• A
  $NH_3$ is less soluble than $PH_3$ in water.
• B
  $NH_3$ is a stronger base and a stronger reducing agent than $PH_3$.
• C
  $NH_3$ has a higher boiling point than $PH_3$ and a lower melting point than $PH_3$.
• D
  $PH_3$ is a stronger reducing agent than $NH_3$ and it has a lower critical temperature than $NH_3$.