Concept:The writer's mood is revealed through the tone of admiration and confidence used to describe teachers.
Explanation:The passage compares teachers to a "noble army" that quietly performs great deeds.
Words like "plants the flag of knowledge and morality" show a positive, forward-looking attitude.
This tone reflects a belief in the meaningful impact of teachers.
It is not excitement, because the writer is calm and respectful.
It is not indifference, as the writer clearly cares deeply.
It is not frustration, since no complaint or disappointment is expressed.
Instead, the writer feels hopeful and encouraging about the teaching profession.
Answer:B. optimism