Why are we given the clue 'la popularité' for the word 'standardisation' and marked wrong when it is used?

Looking at the given answers, I find that the hint is meant to tell you that it is the popularity (la popoularité), which contributes to its standardization, i.e., it refers back to the first part of the sentence. It doesn't mean that you're supposed to use "la popularité" for "standardization".