Ethyne (HCCH)does Not Show IR Absorption in the Region 2000-2500

Multiple Choice

Ethyne (HCCH) does not show IR absorption in the region 2000-2500 cm^-1 because

A) C-H stretches occur at lower energies.
B) CC stretches occur at about 1640 cm^-1.
C) there is no change in the dipole moment when the CC bond in ethyne stretches.
D) there is a change in the dipole moment when the CC bond in ethyne stretches.