Answer:
Correct answer is B) Between the Gulf of Mexico and British-owned Canada.
Explanation:
A is not correct as the southwestern United States are along Pacific Ocean , and this was not a part of the purchase.
B is correct as this was a vast portion of land, that is mostly spreading throughout middle part of US, from Gulf of Mexico to Canadian border.
C is not correct as this part came into possession of the States much later.
D is not correct as eastern part was in the United States since the creation of the country.