Read the given statements and select the correct ones.
(i)Autonomic neural system transmits impulses from the CNS to the voluntary organs and striated muscles of the body.
(ii)Unmyelinated nerve fibres do not have Schwann cells which form the myelin sheath.
(iii)Axonal membrane of a neuron while not conducting any impulse is comparatively more permeable to potassium ions `(K^+)` than to sodium ions `(Na^+)`
(iv)A synapse is formed by the membranes of presynaptic neuron and a post synaptic neuron.

Options

A. (i) and (iv)
B. (ii) and (iii)
C. (iii) and (iv)
D. (i) and (iv)

Explanation

To determine which statements are correct, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (i)**: "Autonomic neural system transmits impulses from the CNS to the voluntary organs and striated muscles of the body."
- **Analysis**: The autonomic nervous system (ANS) actually transmits impulses to involuntary organs (like the heart and digestive organs) and smooth muscles, not voluntary organs or striated muscles (which are controlled by the somatic nervous system).
- **Conclusion**: This statement is **incorrect**.

2. **Statement (ii)**: "Unmyelinated nerve fibres do not have Schwann cells which form the myelin sheath."
- **Analysis**: Unmyelinated nerve fibers can still have Schwann cells, but these Schwann cells do not form a myelin sheath around them. Instead, they may simply surround the unmyelinated fibers without creating a sheath.
- **Conclusion**: This statement is **incorrect**.

3. **Statement (iii)**: "Axonal membrane of a neuron while not conducting any impulse is comparatively more permeable to potassium ions (K⁺) than to sodium ions (Na⁺)."
- **Analysis**: When a neuron is at rest (not conducting an impulse), its membrane is indeed more permeable to potassium ions than to sodium ions. This is due to the presence of more potassium channels compared to sodium channels in the resting state.
- **Conclusion**: This statement is **correct**.

4. **Statement (iv)**: "A synapse is formed by the membranes of presynaptic neuron and a postsynaptic neuron."
- **Analysis**: A synapse is indeed formed between the presynaptic neuron (which sends the signal) and the postsynaptic neuron (which receives the signal). The synapse includes the axon terminal of the presynaptic neuron and the dendrite or cell body of the postsynaptic neuron.
- **Conclusion**: This statement is **correct**.

### Final Conclusion:
The correct statements are **(iii)** and **(iv)**. Therefore, the answer is option **C**: statements 3 and 4 are correct.

---