Answer: $6,000
Step-by-step explanation:
Maria is a citizen and resident of Mexico so the only way the U.S. can tax Maria is by taxing income that is in U.S. jurisdiction before it comes to Maria.
This will include the dividend from ownership of stock in a U.S. Corporation, the interest from a U.S. company issued bond and rental income from a property located in the U.S.
The U.S. will be unable to tax the capital gain from sale of stock however because the sale might not be conducted in the U.S.
Income subject to U.S. taxation is therefore:
= 1,000 + 2,000 + 3,000
= $6,000