Which of the following, according to the Maastricht treaty, was a condition for participating in the common currency area?

A) a relatively small budget deficit-to-GDP ratio
B) at least half the population of the country must speak German, French and English
C) a promise that any future devaluations will be announced in advance
D) the replacement of the country’s prime minister with an appointee of the new “United States of Europe”
E) a relatively small amount of foreign aid to countries outside the area