If the Charge for a Phone Call Were Higher Between

If the charge for a phone call were higher between 8am and 6pm than between 6pm and 8am, this could be explained by the fact that the demand for phone calls is __________ between 8am and 6pm and the demand for phone calls is __________ between 6pm and 8am.

A) zero; one
B) less elastic; more elastic
C) perfectly elastic; perfectly inelastic
D) more elastic; less elastic