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.

Ex Input:
Sentence: An `` optical image stabilizer '' , often abbreviated OIS , IS , or OS , is a mechanism used in a still camera or video camera that stabilizes the recorded image by varying the optical path to the sensor . 
 Question: what is  varied?

Ex Output:
the optical path to the sensor


Ex Input:
Sentence: Although the area was known for its healthy waters at least since the late Middle Ages , the spa was officially founded in 1769 . 
 Question: when was something known  for something?

Ex Output:
since the late Middle Ages


Ex Input:
Sentence: While always referring to oneself or the audience by name would be considered strange in English , in Vietnamese it is considered friendly , and is the preferred way to converse among close friends . 
 Question: who does someone converse?

Ex Output:

among close friends