The correct answer is D) these countries have transitioned to democracy, and the US has decreased aid to them.
The statement that best summarizes how US national security policy has changed in Latin American countries such as El Salvador, Chile, and Nicaragua is " these countries have transitioned to democracy, and the US has decreased aid to them."
With so many problems in their daily lives, these South American and Central American countries are democratic ones than had been receiving less help from the United States. However, democracy for them does not mean that things are doing right in their respective countries. The economy is a big problem in Central American. People from Nicaragua, El Salvador, and Honduras are trying to migrate to the US in thousands, strained in the US-Mexican border.
Right now, people in Chile are taking the streets to protests about economic injustices and poverty that affect their country.
The other options of the question were A) these countries have transitioned to military rule, and the US has increased aid to them. B) these countries have experienced recent Communist revolutions and the US has cut off aid to them. C) these countries have transitioned to democracy and the US has increased aid to them.