- A The anatomical triangular shape that is physically formed by the apex and base of the heart, a structural feature unrelated to limb-lead placement or electrical vector measurement
- B The three limb leads (I, II, III) forming an equilateral triangle around the heart for measuring cardiac electrical activity from different angles
- C The isolated QRS complex waveform that is recorded from a single chest lead alone, a single waveform rather than the geometric arrangement of the three limb leads
- D The combined muscular mass formed jointly by the left and right ventricles together, a description of cardiac muscle mass rather than any electrical lead configuration
Correct answer: B. The three limb leads (I, II, III) forming an equilateral triangle around the heart for measuring cardiac electrical activity from different angles
Explanation: Einthoven's triangle: limb leads I (right arm-left arm), II (right arm-left leg), III (left arm-left leg) form a triangle around the heart. Different angles capture different aspects of electrical axis.
Concept context
Blood, lymph, the heart, the cardiac cycle, blood pressure, and ECG. High NEET weightage.