Read the following statements about the transmission of nerve impulse and select the correct statements.
(i) In a neuron, nerve impulse travels from the dendrite along the axon to its end.
(ii) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in the axon of another neuron.
(iii) Impulses travel across the neurons only in one direction.
(iv) The neurotransmitter released at the post-synaptic membrane, diffuses across the synapse and comes into contact with the chemoreceptor sites in the pre-synaptic membrane.

Options

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

Answer

To solve the question, we need to evaluate each of the statements regarding the transmission of nerve impulses and determine which ones are correct.

### Step-by-Step Solution:

1. **Evaluate Statement (i)**:
- "In a neuron, nerve impulse travels from the dendrite along the axon to its end."
- This statement is **correct**. Nerve impulses are indeed received by the dendrites and then travel through the axon to the axon terminals.

2. **Evaluate Statement (ii)**:
- "The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in the axon of another neuron."
- This statement is **partially correct**. While it is true that chemicals (neurotransmitters) are released and cross the synapse, they do not generate a similar electrical impulse directly in the axon of another neuron. Instead, they bind to receptors on the post-synaptic neuron, which may lead to the generation of a new impulse if the threshold is reached.

3. **Evaluate Statement (iii)**:
- "Impulses travel across the neurons only in one direction."
- This statement is **correct**. The transmission of nerve impulses occurs in one direction, from the dendrites to the axon terminals.

4. **Evaluate Statement (iv)**:
- "The neurotransmitter released at the post-synaptic membrane diffuses across the synapse and comes into contact with the chemoreceptor sites in the pre-synaptic membrane."
- This statement is **incorrect**. The neurotransmitter released from the pre-synaptic neuron diffuses across the synapse to bind with receptors on the post-synaptic membrane, not the other way around.

### Conclusion:
The correct statements are:
- (i) In a neuron, nerve impulse travels from the dendrite along the axon to its end.
- (iii) Impulses travel across the neurons only in one direction.