The following reaction shows the isomerization of alkene A to a more stable alkene B under acidic conditions:

How could IR spectroscopy be used to differentiate them?

The presence of a peak at 3100-3000 cm^-1 in the IR spectrum of alkene A and its absence in the IR spectrum of alkene B can be used to differentiate the two alkenes using IR spectroscopy.

The presence of a peak at 1680-1600 cm^-1 in the IR spectrum of alkene B and its absence in the IR spectrum of alkene A can be used to differentiate the two alkenes using IR spectroscopy.

The presence of a peak at 3100-3000 cm^-1 in the IR spectrum of alkene B and its absence in the IR spectrum of alkene A can be used to differentiate the two alkenes using IR spectroscopy.

The presence of a peak at 1680-1600 cm^-1 in the IR spectrum of alkene A and its absence in the IR spectrum of alkene B can be used to differentiate the two alkenes using IR spectroscopy.