Final answer:
Transitional words or phrases assist in showing the relationship between ideas in sentences or paragraphs.
Explanation:
A transitional word or phrase helps to connect ideas within a sentence or between sentences. It aids in showing relationships and transitions in a text. In the given options, the sentence 'It wasn't until after he left that I finally understood his joke.' uses the transitional phrase 'after' to show the sequence of events.
Learn more about Transitional Words and Phrases here:
https://brainly.com/question/2372495
