Which one of this is the correct use of "one" as a pronoun?

(a) When one reads the Hindi literature of the twentieth century, he finds a striking contrast between the writings of Munshi Premchand and later day writers of popular Hindi fiction.

(b) When one reads the Hindi literature of the twentieth century, one finds a striking contrast between the writings of Munshi Premchand and later day writers of popular Hindi fiction.

According to me, (b) should be the correct one as "one" cannot be used interchangeably with other pronouns when referring to the same thing. But the correct answer is (a). Can someone explain?

Answer

There is not really a “correct” answer. There is no central authority in the English language that decides on the correctness of words or word usage. English is broadly spoken and adapted worldwide and has taken many words from other languages and from slang. The only rule in English is to try and write so that your readers will understand you.

You say that (a) is correct, but it is quite likely that somebody on the opposite side of the world from you is sitting in a classroom right now being taught that (b) is correct.

And here in the United States, if you use either (a) or (b) almost nobody will understand you. We would say:

When you read the Hindi literature of the twentieth century, you find a striking contrast between the writings of Munshi Premchand and later day writers of popular Hindi fiction.