Match List-I with List-II and select the correct answer:
| List-I | List-II |
| a. Li | 1. Time keeper in atomic clocks |
| b. Na | 2. Batteries |
| c. K | 3. Transfer of nerve impulses |
| d. Cs | 4. Control of the water content in the blood |
A. a-2, b-3, c-4, d-1
B. a-1, b-2, c-3, d-4
C. a-2, b-4, c-3, d-1
D. a-1, b-3, c-2, d-4
Answer: Option A

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