History is the study of past events, it's a noun itself and cannot describe the noun 'records' in the sentence. Similarly, a historian is a person who's an expert, or simply a student of history. Both these options are incorrect. The other two options: historical and historic can be confused as the other and often overlaps in meaning. 'Historical' is an adjective that refers to anything from the past whether it is important or not. Not all historical records are important. Option B is hence correct, because they are only providing information of Ashoka's reign (the importance of the event is not mentioned, so let's assume we are referring to all events: important and unimportant) Option D, historic means an event of or relic from the past that is of great importance. Since the records are not of great importance (it is nowhere mentioned that these events are of utmost importance), option D is incorrect.