Final answer:
The Church in the West would have been most likely to B) use leaven bread.
Step-by-step explanation:
The Church in the West would have been MOST likely to use leaven bread. The Latin church, which was prevalent in Western Europe, used leaven bread for the Eucharist. Leaven bread is bread made with yeast, which causes it to rise during baking. This practice was different from the use of unleavened bread in the Greek-speaking Byzantine Empire.
Thus, by using leaven bread (option B), the Church in the West would be following its traditional practice and distinguishing itself from the Eastern Orthodox Church, which uses leavened bread. It is important to note that the use of leavened or unleavened bread can vary within different denominations and local practices, so this answer is specific to the context of the question.