The following title is most appropriate for this chart describe the 19th century:
( D ) The Closing of the West
By Transcontinental Railroad
It increased the land available for American settlement (it only doubled the US's size so it's not that; by this time European influence in America was decreasing and they weren't creating new settlements in North America).
Answer:
They had missionaries travel throughout Europe and win back many of the Europeans who had converted to Protestantism
Explanation: