Weekend Train Travel Costs Less Than Weekday Train Travel

Weekend train travel costs less than weekday train travel. If the supply of train service remains the same between weekdays and weekends, then the most likely explanation for this difference in price is that the weekend

A) supply curve is to the right of the weekday supply curve.
B) demand curve is to the left of the weekday demand curve.
C) demand curve is random.
D) supply curve is to the left of the weekday supply curve.
E) demand curve is to the right of the weekday demand curve.