Final answer:
Unipolar leads in an ECG include the augmented leads and the chest or precordial leads, and they measure electrical potential compared to a zero voltage reference. Standard leads are not unipolar; they are bipolar and measure the voltage difference between two points.
Step-by-step explanation:
The question deals with the types of leads used in an electrocardiogram (ECG or EKG). When we refer to unipolar leads in an ECG, we are discussing leads that measure the electrical potential of one area of the heart compared to a zero voltage reference. The standard ECG includes different types of leads: standard leads (I, II, and III), augmented leads (aVR, aVL, and aVF), and chest (or precordial) leads (V1 to V6). Standard leads are basically bipolar and measure the voltage difference between two points. In contrast, augmented leads and chest leads are unipolar and are referenced against a combination of the other electrodes that provide a zero voltage point.
To answer the question, unipolar leads include all the lead types except A) standard leads, since standard leads are the only bipolar leads in the list provided, and the other options - augmented leads, chest leads, and precordial leads (which are the same as chest leads) - are all unipolar.
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