Explanation: Railroad is a means of transportation used for conveying passengers and goods from one place to another. Rail transport adopt a fixed and standard steel tracks. Trains cannot move on any surface other than these steel tracks. While other means of transportation such as road transport can move on most flat surfaces, Trains follow the directional alignment or positioning of the steel tracks. Railroads as with some other means of transport such as air transport move on fixed schedules where passengers make bookings, board at designated locations and alight at specific stations.
Unlike airplanes and other forms of road transportation that their routes can be altered, have shortcuts, and other routes, railroads are fixed to the ground during construction and hence cannot be altered, hence they operate on fixed routes. Also railroads operate on fixed schedules, except for cases of delays, which seldom happens.
Discrimination is the ability to distinguish between similar stimuli. In this problem, Calista reacts negatively to a typical doctor's office but does not have the same reaction in a dentist's office. This shows she only responds to certain stimuli and does not respond to those that are similar.
I think that this is the answer you're looking for because active listening is an important skill where you really need to concentrate and focus what the other person is trying to say.
