Which of the Following Statements About IR Spectroscopy Is True

Which of the following statements about IR spectroscopy is true?

A) All molecular vibrations can be detected.
B) Absorption of infrared light is associated with both electronic transitions and molecular vibrations.
C) Only vibrations of multiple bonds are observed.
D) For a vibration to be IR active, it must produce a net change in the molecule's dipole moment.
E) Symmetrical vibrations are observed in the IR spectrum, but unsymmetrical vibrations are not.