Read the following statements, A.)Action potential propagates across the neuronal membrane B) Repolarisation decreases the responsiveness of neuronal membrane to further stimulus C) At resting stage, neuronal membrane is negatively charged on the inside and positively charged on the outside. D) For every `2 Na^+` ions which are transported inside the cell, `Na^+ - K^+` pump transports `3K^+` ions to outside,Choose the option which includes correct statements only,

Options

A. a&b
B. a & c
C. b&d
D. a & d

Answer

To solve the question, we need to evaluate each statement regarding neuronal function and determine which ones are correct.

### Step-by-Step Solution:

1. **Evaluate Statement A:**
- **Statement:** "Action potential propagates across the neuronal membrane."
- **Analysis:** This statement is correct. Action potential is indeed the electrical signal that travels along the neuronal membrane, allowing for the transmission of impulses.

2. **Evaluate Statement B:**
- **Statement:** "Repolarisation decreases the responsiveness of neuronal membrane to further stimulus."
- **Analysis:** This statement is incorrect. While repolarization does restore the resting potential, it does not decrease responsiveness. In fact, after repolarization, the neuron can respond to new stimuli, although there may be a brief refractory period.

3. **Evaluate Statement C:**
- **Statement:** "At resting stage, neuronal membrane is negatively charged on the inside and positively charged on the outside."
- **Analysis:** This statement is correct. At rest, the inside of the neuronal membrane is negatively charged relative to the outside due to the distribution of ions, primarily potassium ions and negatively charged proteins.

4. **Evaluate Statement D:**
- **Statement:** "For every 2 Na^+ ions which are transported inside the cell, Na^+-K^+ pump transports 3 K^+ ions to outside."
- **Analysis:** This statement is incorrect. The sodium-potassium pump actually transports 3 Na^+ ions out of the cell and 2 K^+ ions into the cell. Therefore, the statement is not accurate.

### Conclusion:
Based on the evaluations:
- **Correct Statements:** A and C
- **Incorrect Statements:** B and D

Thus, the option that includes the correct statements only is the one that includes A and C.

### Final Answer:
The correct statements are A and C.

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