Since these answers usually are heavily involved with the specifics of the previous position, the specifics aren’t really important. What’s most important is that you actually have been involved in making a suggestion and helping it come to fruition, ideally with some success story behind it. Having done so indicates that you’re willing to do the same at this position, which can do nothing but improve an organization. Not having an answer of some sort here is generally a sizeable negative, but not a “do or die” negative.   _{Your Comment}