Yosef Barbutz,an NRA,is Employed by Fisher,Inc

Yosef Barbutz,an NRA,is employed by Fisher,Inc. ,a foreign corporation.In November,Yosef spends 12 days in the United States performing consulting services for Fisher's U.S.branch.He earns $5,000 per month.A month includes 28 workdays.

A) Yosef has no U.S.-source income under the commercial traveler exception.
B) Yosef has $2,143 U.S.-source income since his foreign employer has a U.S.branch.
C) Yosef has $2,143 U.S.-source income which is exempt from U.S.taxation since he is in the U.S.for 90 days or less.
D) Yosef has $60,000 U.S.-source income which is exempt from U.S.taxation since he is working for a foreign employer.