Final answer:
The absolute refractory period corresponds to the QRS complex in the PQRST complex of an ECG, which represents the depolarization of the ventricles.
During the QRS complex, the heart muscle cells cannot be excited again, indicating the heart is in the absolute refractory phase.
So, the correct answer is:
c) T wave
Step-by-step explanation:
The absolute refractory period in cardiac physiology covers the part of the PQRST complex where the heart muscle is completely unresponsive to further stimulation.
This period corresponds to the QRS complex, which represents the depolarization of the ventricles. During the depolarization represented by the QRS complex, the cardiac muscle cells cannot be depolarized again, which is why this phase is referred to as the absolute refractory period.
The P wave signifies atrial depolarization, which precedes the absolute refractory period. The T wave indicates ventricular repolarization, which follows after the absolute refractory period.
Hence, the absolute refractory period coincides with the QRS complex, and during this time, the atrial repolarization also occurs, but it is masked by the ventricular depolarization represented by the QRS complex.