Correct Answer - `d`
The `(-OH)` group of phenol, unlike that of alchol is difficult to replace by a halogen, e.g. halogen acids have no action, and `PX_(3)` yileds only phosphorous esters. Phenol reacts with `PCl_(5)` or `PBr_(5)`, when the `(-OH)` group of phenol is replaced by a halogen the main product is tripheny phospate.
`(PhO)_(3)P = O` or `Ph_(3) PO_(4)`
Phenol further reacts with `POCl_(3)` to give `Ph_(3)PO_(4)`
