The mayor of a bustling city recently announced a new initiative aimed at improving public transportation. She stated that by increasing the frequency of buses, the city can reduce traffic congestion and make commuting easier for residents. The mayor believes that if more buses are available, more people will opt for public transportation instead of driving their cars.
However, some city planners have pointed out that not all traffic congestion is caused by a lack of public transport options. They argue that factors such as road capacity and the total number of vehicles on the road must also be considered.
Which of the following is an assumption underlying the mayor's argument?