<prompt> Gold Standard investigation for GERD-24 hour pH recordingEndoscopyUltrasoundMagnetic resonance imaging  <response>: Ans. is a i.e., 24 hour pH recording Diagnostic measurement in GERD 24- hour pH recording is the gold standard for diagnosis of GERD TILOSRs are the most important manometric findings in GERD The length and pressure of the LOS are also important 