The boiling points of the Group 15 hydrides (NH3\text{NH}_3NH3, PH3\text{PH}_3PH3, AsH3\text{AsH}_3AsH3, and SbH3\text{SbH}_3SbH3) are shown in the graph below.
Which of the following statements correctly explains the trend shown in the graph?
The boiling point of NH3\text{NH}_3NH3 is higher than that of PH3\text{PH}_3PH3 because the intramolecular N−H\text{N}-\text{H}N−H covalent bonds are much stronger than the P−H\text{P}-\text{H}P−H covalent bonds.
The boiling point increases from PH3\text{PH}_3PH3 to SbH3\text{SbH}_3SbH3 because the electronegativity of the central atom increases down the group, strengthening permanent dipole–dipole attractions.
The anomalously high boiling point of NH3\text{NH}_3NH3 is due to hydrogen bonding between molecules, while the increase from PH3\text{PH}_3PH3 to SbH3\text{SbH}_3SbH3 is due to stronger London dispersion forces.
The boiling point of PH3\text{PH}_3PH3 is lower than that of NH3\text{NH}_3NH3 because PH3\text{PH}_3PH3 has a trigonal planar shape, which prevents effective close packing compared to pyramidal NH3\text{NH}_3NH3.