rural electric cooperative

(I) any organization which is exempt from tax under section 501(a) of title 26 and which is engaged primarily in providing electric service on a mutual or cooperative basis, and

(II) any organization described in paragraph (4) or (6) of section 501(c) of title 26 which is exempt from tax under section 501(a) of title 26 and at least 80 percent of the members of which are organizations described in subclause (I), and