What about D...?

Hi @mprezzy, Happy to help! You are looking for the answer choice which suggests that late flights are not a good indicator of how efficient airline personnel are. So, your focus should have been on examining the efficacy of using that metric for that purpose. There is nothing wrong with measuring an airline's proportion of late flights as a standalone indicator. The issue arises when the agency uses this metric to indicate how efficient airline personnel are in meeting published flight schedules. This is an issue because late flights often occur for reasons that are out of the airline personnel's control (e.g. bad weather conditions as articulated in answer choice (B)). Therefore, answer choice (D) is incorrect because the staff's awareness of the agency monitoring flight times does not necessarily have an impact on the flight schedule. While being aware that they are being monitored might motivate airline personnel to work hard to ensure they meet timelines, it has not impact on factors that are out of their control (e.g. bad weather conditions). In this way, an airline could have the most efficient personnel in the world but still consistently run late because of the weather conditions on their regular routes. Therefore, the proportion of late flights is not a good measure of efficiency of personnel because of the number of factors outside of their control which may impact flight times. I hope this is helpful! Keep up the good work and please let us know if you have any further questions.

@Victoria thank you very much! I understand now.