TASK DEFINITION: In this task, you're given a sentence and question. Based on the information provided in a given sentence, you should identify the shortest continuous text span from the sentence that serves as an answer to the given question. Answer the question using coreference resolution. Coreference resolution is the task of clustering mentions in text that refer to the same underlying real world entities. For example let's take a sentence 'I voted for Obama because he was most aligned with my values, she said.' Here in this example 'I', 'my', and 'she' belong to the same cluster and 'Obama' and 'he' belong to the same cluster. Now let's discuss another example , original sentence: 'I voted for Trump because he was most aligned with my values',John said. Now here is the same sentence with resolved coreferences: 'John voted for Trump because Trump was most aligned with John's values',John said. 
PROBLEM: Sentence: Fred is the only man alive who still remembers my father as an infant. When Fred first saw my father, he was twelve months old. Question: Who was twelve months old?

SOLUTION: father

PROBLEM: Sentence: Tom gave Ralph a lift to school so he wouldn't have to walk. Question: Who wouldn't have to walk?

SOLUTION: Ralph

PROBLEM: Sentence: The doctor informed Kate that she had retired and presented several options for future treatment. Question: Who had retired?

SOLUTION:
doctor