My mistake here was thinking that being regularly tardy and almost never tardy were two different behaviors. I also didn't apply 'not' to 'vow'.

I ruled out E because it's assuming the rate at which carbon dioxide builds up in the cabin is the same in 1980 and today. I thought there were too many factors that would make that untrue, such as maybe the cabins today are sealed better. Also maybe there's more CO2 in the atmosphere today than in 1980.

I feel like they would assume the score was much lower than it really was and all cancelling will do is spark questions for them. Two points is nothing.