Norma, a nonresident alien, deposits $100,000 in a savings account at a U.S. bank. When the U.S. bank pays interest to Norma, it:

(a) must withhold tax at a rate of 30%.

(b) does not have to withhold any tax because of the portfolio interest exemption.

(c) does not have to withhold any tax for interest on bank deposits.

(d) does not have to withhold any tax because the interest constitutes income derived by a foreign central bank from the issuance of bankers acceptances.