A non-resident alien received the following investment income during the current year: $5,000 of dividend income from ownership of stock in a U.S. corporation, $10,000 interest from a certificate of deposit in a U.S. bank, $3,000 of interest income earned from a loan to William, a U.S. citizen, and $2,000 capital gain from sale of a stock in a U.S. corporation. How much of the income will be subject to U.S. taxation?

A $20,000

B $15,000

C $10,000

D $8,000