(2)The deduction specified in sub-section (1) may, at the option of the assessee, be claimed by him for any ten consecutive assessment years out of fifteen years beginning from the year in which the undertaking or the enterprise develops and begins to operate any infrastructure facility or starts providing telecommunication service or develops an industrial park or generates power or commences transmission or distribution of power:Provided that where the assessee begins operating and maintaining any infrastructure facility referred to in clause (b) of Explanation to clause (i) of sub-section (4), the provisions of this sub-section shall have effect as if for the words "fifteen years", the words 'twenty years" had been substituted.
