To answer this question, we need to analyze the information given and determine which statement must be true based on that information.
The given information states that Tim's commute used to be comfortable because there were always seats available on the train. However, since the train schedule changed, the train has become extremely crowded, and by the time the doors open at Tim's station, there are no seats available.
Based on this information, the statement that must be true is:
B. Tim's commute is less comfortable since the train schedule changed.
This statement is true because the given information explicitly states that the train has become extremely crowded and there are no seats available, which implies that Tim's commute has become less comfortable.