Final answer:
A. B. Simpson was the leader of the Christian and Missionary Alliance, a significant American Protestant missionary movement.
Step-by-step explanation:
The Christian and Missionary Alliance (CMA) was a strong missionary movement led by A. B. Simpson. He was a significant figure in the history of American Protestant missions and was deeply involved in the expansion of Christian missions during the late 19th and early 20th centuries. The CMA played a pivotal role in advocating for the spread of Christianity and the American values associated with it, particularly during the period of post-Civil War expansion and the Second Great Awakening that saw the rise of evangelicalism and an increase in missionary activities.