In this task, you are given a sentence and question which can be answered using the sentence. Your task is to answer the question using the information from the sentence. The answer to the question is unique and it is a continuous text span from the sentence.
Q: Sentence: A nonsurgical alternative involves the use of a miotic to constrict the pupil and prevent the lens from luxating into the anterior chamber . 
 Question: what   involves something?
A: 
A nonsurgical alternative