The correct option is D All of the above.
All the trihalides of grouyp 15 elements are stable except NX3. Only NF3 is stable among all the halides of nitrogen.
The reason for the unstability of other trihalides are the bigger size of halogen atom as compared to nitrogen atom. Due to larger size difference in N and halogen the N−X bond becomes weaker hence compound become unstable.
Hence, option (d) is the correct answer.