Answer: veins.
- A veins
- B arteries
- C capillaries
- D nerves
Correct answer: A. veins
Explanation: Veins return blood to the heart.
A single ECG cycle: the P wave marks atrial depolarisation (contraction signal), the large QRS complex marks ventricular depolarisation, and the T wave marks ventricular repolarisation (recovery) before the next cycle begins.
Concept context
Blood, lymph, the heart, the cardiac cycle, blood pressure, and ECG. High NEET weightage.