Definition: 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.

Positive Example 1 -
Input: Sentence: The album is named after the discredited pseudoscience of phrenology , the study of head shapes to determine intelligence and character , which was used to rationalize racism during the 19th century in the United States . 
 Question: what is  named  after something?
Output: The album

Positive Example 2 -
Input: Sentence: The album is named after the discredited pseudoscience of phrenology , the study of head shapes to determine intelligence and character , which was used to rationalize racism during the 19th century in the United States . 
 Question: what was something named  after?
Output: the discredited pseudoscience of phrenology , the study of head shapes to determine intelligence and character , which was used to rationalize racism during the 19th century in the United States .

Negative Example 1 -
Input: Sentence: On September 21 , 1955 , Moore went up in weight to face future Hall of Famer Rocky Marciano for Marciano 's Heavyweight Championship .
 Question: who went up in something?
Output: Rocky

Negative Example 2 -
Input: Sentence: Ladd has won a Golden Globe and a BAFTA and has been nominated three times for the Academy Award for Best Supporting Actress . 
 Question: who has  won something?
Output: Actress

Now complete the following example -
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: how does something stabilize something?
Output: 


Output: by varying the optical path to the sensor