I want to know the answer to the following question:
In what year did Pope Pius IX make his Ex Cathedra proclamation of the Immaculate Conception of Mary?
All the background I'm provided with is that "Orthodox Christians reject the Immaculate Conception dogma principally because their understanding of ancestral sin (the Greek term corresponding to the Latin "original sin") differs from the Augustinian interpretation and that of the Roman Catholic Church.". Is that enough to answer the question?
Answer: no