The correct option is (d) Acetic acid
To explain I would say: Sodium dodecyl sulfate or SDS is a strong denaturant of protein and is used in SDS-PAGE technique. DTT is oftentimes used along with SDS to further denature proteins by reducing their disulfide bonds to allow for better separation of proteins during electrophoresis. Phenol is used as a protein denaturant during isolation of RNA from plants.