This is a bad question. Don't study it.

Now, nothing's wrong with D grammatically. But then nothing's wrong with B grammatically either. I found this on the original site and that site claimed that "inspiring" in B incorrectly refers to "barrier." "comma + -ing form" setups are not noun modifiers. They are adverbial modifiers, meaning they modify the entire preceding clause. And that's perfectly fine in this case.

You basically have two right answers here. In fact, if I had to choose, I'd say that B is better than D because B exactly maintains the original meaning that "breaking the psych barrier" leads to inspiring others, while D says that the "sub-four-minute mile" leads to inspiring others. Even there, though, it's next to impossible to choose, because the sub-four-minute mile is the thing that broke the psych barrier, so it's basically the same thing! There's not truly a meaning change there.

In a nutshell: don't use this question to study. It's not representative of the GMAT.