Which of the following statements is correct?

Options

A. Some tranquilisers function by inhibiting the enzymes which catalyse the degradation of noradrenaline.
B. Tranquilisers are narcotic drugs.
C. Tranquilisers are chemical compounds that do not affect the message transfer from nerve to receptor.
D. Tranquilisers are chemical compounds that can relieve pain and fever.

Answer

To determine which of the statements regarding tranquilizers and their functions is correct, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding Tranquilizers**:
- Tranquilizers are drugs that have a calming effect on the nervous system. They are primarily used to treat anxiety and other psychological conditions.

2. **Analyzing Statement 1**:
- "Some tranquilizers function by inhibiting the enzyme that catalyzes the degradation of noradrenaline."
- This statement is correct. Some tranquilizers do work by inhibiting enzymes that break down neurotransmitters like noradrenaline, thereby increasing their levels in the synaptic cleft and enhancing their calming effects.

3. **Analyzing Statement 2**:
- "Tranquilizers and narcotic drugs."
- This statement is misleading. While both are used to treat different conditions, tranquilizers are not classified as narcotics. Narcotics are primarily pain-relieving medications.

4. **Analyzing Statement 3**:
- "Tranquilizers are chemical compounds that do not affect the message transfer from nerve to receptor."
- This statement is incorrect. Tranquilizers do affect the message transfer by modulating the activity of neurotransmitters, thus influencing communication between nerves and receptors.

5. **Analyzing Statement 4**:
- "Tranquilizers are chemical compounds that can relieve pain and fever."
- This statement is also incorrect. Tranquilizers are not primarily used for pain relief or fever reduction; they are used to alleviate anxiety and stress.

6. **Conclusion**:
- After analyzing all statements, the only correct statement is the first one. Therefore, the answer is that the first statement is correct.

### Final Answer:
The correct statement is: **Some tranquilizers function by inhibiting the enzyme that catalyzes the degradation of noradrenaline.**

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