Answer- B. -PCR for virusDetection of rabies virus RNA by - PCR is highly sensitive and specific. This technique can detect virus infresh saliva samples, skin, CSF, and brain tissues.Detection of rabies virus RNA by -PCR is highly sensitive and specific. This technique can detect virus in fresh saliva samples, skin, CSF, and brain tissues. In addition, -PCR with genetic sequencing can distinguish among rabies virus variants, permitting identification of the probable source of an infection."-Harrison 19/e p1302.Reverse transcription-polymerase chain reaction testing can be used to amplify pas of a rabies virus genome from fixed or unfixed brain tissue or saliva. Sequencing of amplified products can allow identification of the infecting virus strain.