Answer: D. Dollarization
Explanation: Ecuador officially changing its currency to the US dollar means that it has substituted its Sucre with the Dollar. This is termed dollarization, also known as currency substitution, a process whereby a country, officially, or its residents, unofficially, adopting the US dollar or other foreign currency in parallel to or instead of the domestic currency. It has its advantages as well as disadvantages. Some of the advantages include lower administrative costs, a firm basis for a sounder financial sector, and lower interest rates. Its disadvantages ranges from the loss of monetary autonomy, national symbol as well as greater vulnerability to foreign influence among others.