Question

When an American household purchases a bottle of Italian wine for $100,

1U.S. consumption does not change, U.S. net exports decrease by $100, and U.S. GDP decreases by $100.

2U.S. consumption does not change, U.S. net exports increase by $100, and U.S. GDP increases by $100.

3U.S. consumption increases by $100, U.S. net exports decrease by $100, and U.S. GDP does not change.

4U.S. consumption increases by $100, U.S. net exports do not change, and U.S. GDP increases by $100.

WHY？