The compound that causes general antidepressant action on the central nervous system belongs to the class of

Options

A. analgesics
B. tranquilizers
C. narcotic analgesics
D. antihistamines.

Answer

To solve the question regarding which class of compounds causes general antidepressant action on the central nervous system, we can analyze the options provided:

1. **Analgesics**: These are compounds that primarily provide relief from pain. They do not have a direct antidepressant effect on the central nervous system.

2. **Tranquilizers**: These compounds are known to have a calming effect and can help alleviate anxiety and depression. They act on the central nervous system and are often used as antidepressants.

3. **Narcotic analgesics**: While these compounds provide relief from pain and can induce sleep, they are not primarily used for their antidepressant properties.

4. **Antihistamines**: These drugs work by blocking the action of histamine in the body. They are not primarily used for antidepressant effects.

Based on this analysis, the correct answer is that the compound causing general antidepressant action on the central nervous system belongs to the class of **tranquilizers**.

### Step-by-Step Solution:
1. **Identify the function of each option**:
- Analgesics relieve pain.
- Tranquilizers have calming effects and can act as antidepressants.
- Narcotic analgesics relieve pain and induce sleep.
- Antihistamines block histamine action.

2. **Determine which option relates to antidepressant action**:
- Tranquilizers are the only class that is specifically known for having a general antidepressant action on the central nervous system.

3. **Conclude the correct answer**:
- The answer is **tranquilizers**.