There is a need to raise teachers' salary in order to boost their …

Analyze the question: The sentence is "There is a need to raise teachers' salary in order to boost their __." We need a word meaning the confidence, enthusiasm and discipline of a group of people at work.

Explain the concept: This is a question on commonly confused words (lexis).

• Morale (noun): the level of confidence, enthusiasm and cheerfulness of a person or group. Example: "Low pay lowers workers' morale."
• Moral (noun or adjective): as an adjective it means concerning right and wrong. As a noun it means the lesson of a story, e.g. "The moral of the story is honesty."
• Spirit: a person's inner nature or mood, or a ghost. It can sometimes be used loosely, as in "team spirit", but "boost their spirit" is not the standard phrase here. The usual form is "boost their spirits" or "boost their morale."
• Soul: the spiritual part of a person. It does not fit a discussion of pay and work motivation.

Solution:

1. Raising salaries affects how motivated and confident workers feel.
2. The collocation "boost morale" is standard English, as in "boost workers' morale."
3. "Moral" (B) is a spelling and meaning trap, because it sounds similar but refers to right and wrong.
4. "Spirit" (A) is close, but it is singular and not the standard collocation. "Soul" (C) is clearly out.

So the best answer is D. morale.

Tip: "Morale" ends in -le and is stressed on the second syllable (mo-RALE). Remember "boost the morale" and "teach a moral." If the sentence is about motivation at work, in the army or on a sports team, choose morale.