(a)in the case of an individual,--(i)by the individual himself;(ii)where he is absent from India, by the individual himself or by some person duly authorised by him in this behalf;(iii)where he is mentally incapacitated from attending to his affairs, by his guardian or any other person competent to act on his behalf; and(iv)where, for any other reason, it is not possible for the individual to sign the return, by any person duly authorised by him in this behalf:
