The Use of Road Tolls to Reduce Traffic Can Be

The use of road tolls to reduce traffic can be desirable for which of the following reasons?
(i) they charge people according to consumption
(ii) they can help bring usage closer to its optimal level
(iii) rates can differ according to the time of day
(iv) the administrative costs are virtually non-existent

A) (i) and (ii)
B) (ii) and (iii)
C) (ii) , (iii) and (iv)
D) (i) , (ii) , and (iii)