Which organizational pattern would probably be most effective for arranging the main points of a speech with the specific purpose “To persuade my audience that ivory trade should be banned”?

Which organizational pattern would probably be most effective for arranging the main points of a speech with the specific purpose “To persuade my audience that ivory trade should be banned”?
A.problem-solution
B.thematic
C.persuasive
D.causal
正确答案：problem-solution