The songhai empire expanded its wealth and power by A) destroying its Christian neighbors
B) winning control over trade routes
C) developing ways to reverse desertification
D) defeating invading muslim armies

B. winning control over trade routes.

Explanation:

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i think the answer is c

explanation:

c. print money only as needed

1 > george s. boutwell

2 > general ulysses s. grant

3 > james a. garfeild

4 > adolph e. borie