Tendon of Todaro
Septal leaflet of tricuspid valve
Answer A) AV Node
Explanation: The triangle of Koch can be seen in the image
Koch’s triangle, named after the German pathologist and cardiologist Walter Karl Koch, is an anatomical area located in the superficial paraseptal endocardium of the right atrium.
Its boundaries are the coronary sinus orifice, tendon of Todaro, and septal leaflet of the right atrioventricular valve.