When working through this I chose the right answer, (B), but looking back on the question - "which one would the author most likely say is the most troublesome barrier ... " I feel uneasy about it. How would you recommend going through the passage to find what the author feels is most important? I just went with my gut, which told me that the author talks about the inflexibility of work schedules for a long time in the beginning of the passage. But I would love to know if there is a better way to go about it.

Thanks!