(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?