How many of the following statements is/are correct?
(i) Multipolar neurons have a single axon and multiple dendrites
(ii) Unipolar neurons have a cell body with one axon only .
(iii) The myelinated nerve fibres are enveloped with Schwann cells.
(iv) The postsynaptic neurons are filled with neurotransmitter containing vesicles.

Options

A. One
B. Two
C. Three
D. None

Answer

To determine how many of the given statements are correct, we will analyze each statement one by one.

### Step 1: Analyze Statement (i)
**Statement (i):** Multipolar neurons have a single axon and multiple dendrites.

**Analysis:** This statement is correct. Multipolar neurons are characterized by having one axon and multiple dendrites. This structure allows them to receive input from multiple sources.

### Step 2: Analyze Statement (ii)
**Statement (ii):** Unipolar neurons have a cell body with one axon only.

**Analysis:** This statement is also correct. Unipolar neurons consist of a single process that extends from the cell body, which branches into an axon and a dendrite. Thus, they have one axon.

### Step 3: Analyze Statement (iii)
**Statement (iii):** The myelinated nerve fibers are enveloped with Schwann cells.

**Analysis:** This statement is correct. Schwann cells are responsible for forming the myelin sheath around myelinated nerve fibers in the peripheral nervous system. They wrap around the axon, providing insulation.

### Step 4: Analyze Statement (iv)
**Statement (iv):** The postsynaptic neurons are filled with neurotransmitter containing vesicles.

**Analysis:** This statement is incorrect. It is the presynaptic neurons that contain vesicles filled with neurotransmitters. The postsynaptic neurons have receptors that bind to these neurotransmitters but do not contain the vesicles themselves.

### Conclusion
Now, let's summarize the correctness of each statement:
- Statement (i): Correct
- Statement (ii): Correct
- Statement (iii): Correct
- Statement (iv): Incorrect

Thus, out of the four statements, three are correct.

### Final Answer
**Three statements are correct.**

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