9. A computer program product comprising a non-transitory computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to: responsive to identifying an input question as an explanatory question, decompose the explanatory question into one or more explanatory queries; identify one or more passages within a corpus of information that comprise an explanatory clause that provides an explanatory answer to the explanatory question based on pre-determined explanatory clause terms, wherein a passage within the one or more passages within the corpus of information that comprises the explanatory clause is identified by the computer readable program further causing the computing device to: compare each identified clause within a passage to a set of previously identified explanatory clauses; and responsive to the identified clause within a passage corresponding to one of the set of previously identified explanatory clauses, tag the clause within the passage with an ‘EXPLANATORY’ tag; receive hypothesis evidence with one or passages comprising explanatory clauses from the corpus of information; generate one or more candidate explanatory answers based on hypothesis evidence; rank and merge the one or more candidate explanatory answers; and output the one or more candidate explanatory answers.
13. The computer program product of claim 9 , wherein the computer readable program to identify the input question as the explanatory question further causes the computing device to: parse the input question for a beginning and ending portion of the input question; compare the beginning and ending portion of the input question to a predetermined set of explanatory question rules; and responsive to the input question corresponding to one of the predetermined set of explanatory question rules, tag the input question as an ‘EXPLANATORY’ question.