A. The car fuel costs are slated to rise in the coming months.
We already know that train is more efficient than car in terms cost and time-to-travel. So further stating that train will be even more cost-effective may slightly strengthen the argument
B. Commuting by train is more comfortable and also frees people to use the commuting time constructively.
This one adds one more reason that train has advantages over car. It slightly strengthens the argument
C. The train's timings are fixed and do not depend on traffic conditions
We already know that trains are time effective so adding how they happen do so doesn't really add any value here
D. The new business center coming up in downtown Salmaville will increase the commuter population between the twin cities
Increasing the commuter population may or may not be a good thing. This one isn't even tangent to our argument
E. Travel time and cost are the two most important considerations for the working population in deciding the mode for commuting to the workplace.
CorrectIf Time and cost are the most important things, then we are inclined to believe that people will switch to trains. This choice successfully dissipate the effect of any other extraneous element that may play a role in deciding the type of travel