Evaluate the reasons and select the correct response: what sparked the spread of christianity by the greek orthodox church into eastern europe?

Christianity made its way into Eastern Europe during 9th and 10th centuries. This was the period when Byzantium's churchmen Patriarch Photios initiated the Christianization of the Slavs.After the Fall of Constantinople, Orthodox Christians were under the Ottoman Turkish rule. When they regained their independence, they organized Orthodox churches in the Southern and Eastern Europe.