What World Event Helped Christianity Spread Rapidly After a Few

Multiple Choice

What world event helped Christianity spread rapidly after a few centuries of being a minor and persecuted religion?

A) The fall of the Ottoman Empire
B) Its adoption as the official religion of the Roman Empire
C) The invention of the printing press, which allowed the Bible to be produced more cheaply and efficiently that priests copying it by hand could work
D) The invention of vaccinations, which allowed Christians who used them to survive disease outbreaks at a higher rate than non-Christians who did not use them