What Constitutes Evidence for the Efficacy of the Congestion Charge

Multiple Choice

What constitutes evidence for the efficacy of the congestion charge described in the text?

A) The total emission from vehicles in the regulated area of London declined after the introduction of the congestion charge.
B) The distance traveled by all private vehicles in the regulated area of London declined after the introduction of the congestion charge, while more distance was traveled by public transportation.
C) The distance traveled by private vehicles in the regulated area of London declined after the introduction of the congestion charge, while more distance was traveled by high-occupancy vehicles and low-emission vehicles.
D) The revenue to the city government of London has dramatically increased.