“provident fund”, in relation to any person, means –

(a)     a fund which has in respect of the year of assessment in question or any previous year of assessment been approved by the Commissioner as a provident fund as defined in section 1 of this Act or the corresponding provisions of any previous Income Tax Act; or

(b)     a public sector fund, the rules of which provide for benefits in a lump sum exceeding one–third of the capitalised value of all benefits (including lump sum payments and annuities) to its members on retirement,

if during any such year the person was a member of such fund;