Answer:
D It adds a specific detail about place that is relevant to the text’s topic.
Step-by-step explanation:
An infinitive phrase is a sentence that contains an infinitive in a sentence that modifies a verb and expresses action in a sentence. It is easily detected or identified by the word "-to" which usually is the start of the infinitive phrase.
In the given passage, the infinitive phrase "to see a Broadway play" presents a specific place that is relevant to the main topic of the text. The work done and the money raised will all lead up to the finalizing of the plans that they had, which was "a trip to the city to see a Broadway play".
Thus, the correct answer is option D.