This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
'c' wave of JVP 
Select and explain. 
A. Occurs during rapid filling phase of cardiac cycle, B. Occurs due to opening of tricuspid valve, C. Occurs due to closure of tricuspid valve into right atrium, D. Occurs at the end of T wave
C: Occurs due to closure of tricuspid valve into right atrium
Answer: C: Occurs due to closure of tricuspid valve into right atrium 
Explanation: c' wave of JVP

Occurs due to bulging of tricuspid valve into right atrium
Occurs during isovolumetric contraction phase
In tricuspid regurgitation, v wave merge with c wave.