Darkness : Lamp :: ?

Options

A. Fatigue : Exercise
B. thirst : Water
C. Medicine : Illness
D. Study : Classroom

Explanation

To solve the analogy "Darkness : Lamp :: ?," we need to identify the relationship between the first pair and apply the same relationship to find the missing pair.

### Step-by-Step Solution:

1. **Identify the Relationship in the Given Pair:**
- The first term is "Darkness," and the second term is "Lamp."
- A lamp provides light, which eliminates darkness. Therefore, the relationship is that the second term (Lamp) eliminates the first term (Darkness).

2. **Look for Similar Relationships in the Options:**
- We need to find a pair where the second term eliminates the first term, just like the lamp eliminates darkness.

3. **Evaluate the Options:**
- **Option A: Fatigue : Exercise**
- Exercise can reduce fatigue, but it doesn't completely eliminate it. This does not fit our relationship.
- **Option B: Thirst : Water**
- Water quenches thirst. Here, water (the second term) eliminates thirst (the first term). This fits our relationship.
- **Option C: Medicine : Illness**
- Medicine can cure or alleviate illness, but it doesn't always eliminate it completely. This does not fit our relationship.
- **Option D: Study : Classroom**
- A classroom is a place for study, but it does not eliminate the concept of study. This does not fit our relationship.

4. **Conclusion:**
- The correct answer is **Option B: Thirst : Water**, as water eliminates thirst in the same way that a lamp eliminates darkness.

### Final Answer:
**Thirst : Water**