Chemical Bonding and Molecular Structure

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): $\mathrm{PH}_3$ has lower boiling point than $\mathrm{NH}_3$. Reason (R) : In liquid state $\mathrm{NH}_3$ molecules are associated through vander Waal's forces, but $\mathrm{PH}_3$ molecules are associated through hydrogen bonding. In the light of the above statements, choose the most appropriate answer from the options given below :