(2)The option under this section shall be exercised by the assessee in the manner as may be prescribed subject to the following conditions:––(a)it shall be exercised on or before the due date specified under section 263(1) for furnishing the first of the returns of income for any tax year; and(b)such option, once exercised, shall apply to subsequent tax years;(c)once the option has been exercised for any tax year, it shall not be subsequently withdrawn for the same or any other tax year;(d)where the assessee fails to fulfil the conditions contained in sub-section (1) (Table: Sl. No. 1. B) in any tax year,––(i)the option shall become invalid in respect of such tax year and subsequent tax years; and(ii)the other provisions of this Act shall apply, as if the option had not been exercised for that tax year and subsequent tax years.