Answer:
A. A warrior should not be seduced by fame.
B. A warrior should take advantage of material gain.
C. A warrior must first endure pain to be happy.
D. A warrior must think of his work as a game to be happy
Explanation:
Options B, C, and D are all facts.
Meaning A, the only option left, is an opinion
Tends to emphasize the differences between writer and reader, and makes the message easier to understand