Which of the following correctly pairs a transition with its most closely associated region of the electromagnetic
spectrum?

Answer:
D
Explanation:
The vibration of molecules is studied using infrared spectroscopy. Infrared spectroscopy is used to study the various modes of vibration of a molecule.
Infrared spectroscopy is used to is used to identify various functional groups by observing their stretching frequencies.
For a molecule to be infrared active, the molecule must give rise to a change in the molecular electric dipole moment.