Answer:
B. Production from a U.S. firm that operates in Mexico
Explanation:
GNP is the sum of all final goods and services produced by a country's nationals in a given year.
In the calculation of GNP, production of foreign residents are excluded. Therefore, Production from an Hungarian citizen who works in Denver, CO and Production from a Canadian firm that operates in Montana would be excluded.
Only production from US nationals irrespective of where the production takes place would be included.
I hope my answer helps you.