• Tandem Mass Spectrometry Terminology:
• In LC-MS/MS and GC-MS/MS using triple quadrupole ($QqQ$) mass spectrometers, MRM stands for Multiple Reaction Monitoring.
• In MRM, the first quadrupole ($Q_1$) selects a specific precursor ion, the collision cell ($q_2$) fragments it using collision-induced dissociation (CID), and the third quadrupole ($Q_3$) monitors specific characteristic product ions, providing extraordinary selectivity and sensitivity for trace residue quantitation.
• Conclusion: MRM stands for Multiple Reaction Monitoring (Option 2).

Correct option: (2) Multiple reaction monitoring

• Orbitrap Mass Spectrometer Capabilities:
• The Orbitrap mass analyzer (invented by Alexander Makarov) captures ions in electrostatic oscillation around a central spindle electrode, determining $m/z$ from the harmonic axial oscillation frequency.
• It is globally celebrated in metabolomics and pesticide residue analysis for providing ultra-high mass resolving power ($\gt 100,000$ to $500,000$) and sub-ppm accurate mass measurement, enabling unambiguous elemental formula determination of unknown analytes.
• Conclusion: Orbitrap is primarily used for Accurate Mass determination (Option 1).

Correct option: (1) Accurate mass