The correct answer is C) Vikings became less willing to attack Christian lands.
The role that the conversion of Vikings to Christianity played in integrating them into Europe was that Vikings became less willing to attack Christian lands.
Vikings were from Scandinavia. Most Vikings were pagans and attacked Christian monasteries, not for religious purposes but because in the monasteries were food and richness and had no defense at all, making the job easy for the Vikings.
But during the Viking age after their raids on towns they had contact with Christian beliefs and had no problem to leave their many gods behind to adopt Christianity. They did so in Ireland, Normandy, and the British islands. Years later, missionaries arrived in Scandinavia in the 11th century and established Christianity in Norway and Denmar