Natives would sometimes mix marriages with those from.

a. Spain

b. France

c. Portugal

I am pretty sure the answer is A, Spain.

I would say it's A.) Spain

... since the Spaniards basically mixed with the Natives in most South/Central and North America. This is why "Mestizos" exist because many Spaniards would mix with the Natives and create a Mestizo "mixed" race.