The answer is contrast or opposition
Explanation:
Transitional words or phrases include but, or, for example, firstly, among others. These are used as part of the language to indicate the relationship between elements and connect ideas. In the sentence presented, the transitional word "but" connects the detail "it was dirty."
Moreover, these words can show different relationships between details including similarity, contrast, order, emphasis, exemplification, among others. In the case of "but" this shows contrast or opposition. This relationship occurs in the sentence presented because the transitional word helps the speaker clarify that specific Monday the woman could not wear the skirt (but it was dirty) even when she always did it (she always wore her blue skirt on Mondays.)
