A U$.$S$.$ corporation owns notes payable issued by a foreign partnership on which it received interest income of $$100,000$ during the

Attem current year. The foreign partnership has a branch operation in the U$.$S$.($representing $60\%$ of its business$)$ and the interest paid is $60\%$ attributable to the U$.$S$.$ branch operations. What is the source of the $$100,000$ of interest income to the U$.$S$.$ corporation?

$$100,000$ U$.$S$.-$source.

$$100,000$ foreign$-$source.

$$60,000$ U$.$S$.-$source and $$40,000$ foreign$-$source.

None of the above.