A dilute solution of 1,3-pentanediol [HOCH2CH2CH(OH)CH2CH3] in CCl4 does not produce the characteristic IR signal for a dilute alcohol. Rather, it produces a broad signal that is characteristic of a concentrated alcohol. Choose the correct explanation for the observed signal.
a. The compound exhibits intramolecular hydrogen bonding even in dilute solutions.
b. Electron-withdrawing induction effects shift the absorption spectrum to a lower wavenumber than would be observed in a compound containing a single "OH" unit.
c. Electron-donating induction effects shift the absorption spectrum to a higher wavenumber than would be observed in a compound containing a single "OH" unit.
d. The compound exhibits increased resonance at dilute concentrations, which increases the effective concentration.