ForCo, a foreign corporation not engaged in a U.S. trade or business, recognizes a $3 million gain from the sale of land located in the United States. The amount realized on the sale was $6 million. Absent any exceptions, what is the required withholding amount on the part of the purchaser of this land?

a. $200,000

b. $500,000

c. $600,000

d. $1.5 million

e. $5 million