The correct choice is (b) Biocatalyst
For explanation I would say: Biocatalyst is used on biosensor to convert substrate to product, and not mass spectrometer. Mass spectrometer is used to determine molecular weight based on the charge to mass ratio. There are 3 main parts of the mass spectrometer:
• Ion source: The sample is vaporized into a gas and then ionized by the ion source, usually by losing an electron to become a cation.
• Mass analyzer: The ions are then accelerated through a potential difference and focused into a beam to give all species the same kinetic energy.
• Deflection: The ion beam passes through a magnetic field which bends the charged stream.
• Detector: The number of ions at different deflections are counted by the detector.