A : Transmission of the nerve impulse across a synapse is accomplished by neurotransmitters .
R : Transmission across a synapse usually requires neuro transmitters because there is space , i.e., synaptic cleft, that separates one neuron from another .

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question presents two statements:
- A: "Transmission of the nerve impulse across a synapse is accomplished by neurotransmitters."
- R: "Transmission across a synapse usually requires neurotransmitters because there is a space, i.e., synaptic cleft, that separates one neuron from another."

2. **Analyzing Statement A**:
- The first statement (A) is about the role of neurotransmitters in the transmission of nerve impulses.
- Neurotransmitters are indeed the chemical messengers that facilitate communication between neurons at the synapse.
- Therefore, statement A is **true**.

3. **Analyzing Statement R**:
- The second statement (R) explains why neurotransmitters are necessary for transmission across the synapse.
- It mentions the presence of the synaptic cleft, which is the gap between the presynaptic neuron (sending neuron) and the postsynaptic neuron (receiving neuron).
- This cleft prevents direct electrical transmission, necessitating the use of neurotransmitters to bridge the gap.
- Thus, statement R is also **true**.

4. **Determining the Relationship**:
- Now, we need to determine if R is the correct explanation for A.
- Since R explains that the synaptic cleft requires neurotransmitters for transmission, it directly supports the assertion made in A.
- Therefore, R is indeed the correct explanation for A.

5. **Conclusion**:
- Both statements A and R are true, and R correctly explains A.
- The correct answer is that both A and R are true, and R is the correct explanation for A.

### Final Answer:
Both A and R are true, and R is the correct explanation for A.

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