How many electrodes are used in a 12 lead ECG?

In a 12-lead ECG, a total of 10 electrodes are used to create the 12 different electrical views of the heart. This includes 4 limb electrodes (typically placed on the right arm, left arm, right leg, and left leg) and 6 chest electrodes placed at specific positions across the chest. The 10 electrodes allow for the recording of 12 leads because the ECG machine converts the information from the electrodes into 12 unique perspectives, or leads, that reflect the heart's electrical activity from different angles. Each lead provides important insights into the heart's rhythm and activity, making the 12-lead ECG a crucial tool in clinical practice for diagnosing various cardiac conditions.

The other options do not reflect the correct configuration of the electrodes used in a standard 12-lead ECG. For instance, having only 6 electrodes would not provide enough coverage to capture the necessary leads, and while 12 electrodes suggest that each lead is represented by its own electrode, that is not how the lead system functions in this context.