section 501(c)(4) organization with respect to which— (1) the amount of contributions provided to the organization by foreign nationals described in subparagraph (C) of section 319(b)(1) was equal to or greater than 5 percent of the gross receipts of the organization, as determined on the basis of the most recent taxable year for which information on the gross receipts of the organization is available or, in the case of an organization which is required to file quarterly reports with the Securities and Exchange Commission under section 13 of the Securities Exchange Act of 1934 ( 15 U.S.C. 78m ), the most recent such report