Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            owing the heart to refill.
3. Heart Sounds and Waveforms Correlation
The heart sounds can be correlated with specific points on the ECG:
 
S1 occurs just after the QRS complex as the ventricles begin to contract.
 
S2 follows the T wave, marking the end of ventricular contraction and the 
beginning of diastole.
Diastole and Systole
The total duration of the cardiac cycle, including systole and diastole, is the 
reciprocal of the heart rate. For example, if the heart rate is 72 beats/min, 
the duration of the cardiac cycle is 1/72 min/beat—about 0.0139 min/beat. 
Figure below shows the different events during the cardiac cycle for the left 
side of the heart. The top three curves show the pressure changes in the
aorta, left ventricle, and left atrium, respectively. The fourth curve depicts the
changes in left ventricular volume, the fifth depicts the electrocardiogram, 
and the sixth depicts a phonocardiogram, which is a recording of the sounds
produced by the heart—mainly by the heart valves—as it pumps. It is 
especially important that the reader study this figure in detail and 
understand the causes of all the events shown.
Increasing Heart Rate Decreases Duration of Cardiac
Cycle. 
When heart rate increases, the duration of each cardiac cycle 
decreases, including the contraction and relaxation phases. The 
duration of the action potential and systole also decrease, but not by as 
great a percentage as diastole. At a normal heart rate of 72 beats/min, 
systole comprises about 0.4 of the entire cardiac cycle. At three times 
the normal heart rate, systole is about 0.65 of the entire cardiac cycle. 
This means that the heart beating very rapidly does not remain relaxed 
long enough to allow complete filling of the cardiac chambers before 
the next contraction.
Clinical Relevance
1. Heart Sound Abnormalities
Abnormal heart sounds can provide significant insights into cardiac pathology. For example:
  
A murmur is an abnormal sound often caused by turbulent blood flow, which can indicate 
valve disorders.
   The presence of S3 or S4 can indicate heart failure or stiff ventricles, respectively.
2. Interpretation of ECG
The interpretation of ECG waveforms is crucial in diagnosing various cardiac conditions, 
such as arrhythmias, myocardial infarction, and electrolyte imbalances. Understanding the 
relationship between heart sounds and ECG findings aids in comprehensive patient 
assessment.
3. Advances in Technology
Recent advancements in technology, such as portable ECG devices and artificial 
intelligence in cardiac monitoring, have improved the ability to detect heart conditions and 
enhance patient outcomes.
Conclusion
Understanding the heart sounds and waveforms generated 
during the cardiac cycle is vital for diagnosing and managing 
cardiovascular conditions. By correlating heart sounds with the 
phases of the cardiac cycle and the associated ECG 
waveforms, medical professionals can develop a deeper 
understanding of cardiac function and path

            Quiz: