Under what condition may it be to the taxpayer's advantage to take a deduction for total foreign taxes paid rather than a tax credit for foreign income taxes?

a) If the foreign income tax rate is greater than the U.S. federal income tax rate

b) If the foreign income tax rate is less than the U.S. federal income tax rate

c) If foreign source income is less than domestic income

d) If foreign taxes other than the income taxes are substantial