Final answer:
A US citizen who owns stock in a Canadian company and has taxes withheld on dividends can claim a foreign tax credit on their U.S. tax return to prevent double taxation.
Step-by-step explanation:
When a US citizen owns stock in a Canadian company and receives dividends, the Canadian government withholds a portion of those dividends as a tax. Specifically, if the Canadian government withholds 15% of the dividends as a tax, the US investor can report this as a foreign tax credit on their U.S. tax return. Thus, the correct answer is C) a tax credit on the investor's U.S. tax return. This prevents double taxation, as the investor will be credited for taxes paid to a foreign government when they file their taxes in the United States.