The nodal musculature of the heart has the capability to generate impulse:
| 1. | on stimulation by the sympathetic division of the autonomic nervous system |
| 2. | on stimulation by the parasympathetic division of the autonomic nervous system |
| 3. | on stimulation by the somatic neural division of the peripheral nervous system |
| 4. | without any external stimulus |
Match each item in Column-I with one in Column-II and select the correct answer from the codes given:
| Column-I | Column-II | ||
| A. | Closure of AV valves | a. | Second heart sound |
| B. | Closure of semilunar valves | b. | First heart sound |
| C. | Opening of AV valves | c. | Ventricular ejection |
| D. | Opening of semilunar valves | d. | Passive ventricular filling |
Codes:
| A | B | C | D | |
| 1. | a | b | c | d |
| 2. | b | a | c | d |
| 3. | b | a | d | c |
| 4. | a | b | d | c |