Chang, an NRA, Is Employed by Fisher, Inc

Chang, an NRA, is employed by Fisher, Inc., a foreign corporation.In November, Chang spends 12 days in the United States performing consulting services for Fisher's U.S.branch.She earns $5,000 per month.A month includes 20 workdays.

A) Chang has no U.S.-source income, under the commercial traveler exception.
B) Chang has $3,000 U.S.-source income, since her foreign employer has a U.S.branch.
C) Chang has $60,000 U.S.-source income which is exempt from U.S.taxation, since she is in the U.S.for 90 days or less.
D) Chang has $60,000 U.S.-source income which is exempt from U.S.taxation, since she is working for a foreign employer.