How Did the Principle Aim of Early Missionaries Change After

How did the principle aim of early missionaries change after attempts at preaching to the local populations?

A) They discovered they were more successful appealing to people on a spiritual level,as opposed to theological debate.
B) They found they were more successful dealing with people's humanitarian needs rather than their religious needs.
C) Their programs changed quickly from religious missions to commercial enterprises.
D) The missionaries quickly learned they should assimilate into the local culture and avoid trying to Americanize the local people.