Answer:


Well A-B is off by 0.060 A and B-C is off by 0.091 A. So B-C is almost twice as far off as A-B. But.... A-B is actually off by 4 standard deviations, and thus has a Z-score of 4 while the Z-score on B-C is less than 2. So A-B is worst. (Albeit that I have implicitly assumed that the number of standard deviations that a bond is away from ideal is a measure of badness; obviously you can make another decision for yourself but don't because that would make the rest of this practical difficult).