The correct option is C Marcello Malpighi
Capillaries are the thinnest blood vessels which are present in the organs. The walls of capillaries have only a layer of the endothelium in which the cells are flat and squamous.
The exchange of gases, nutrients and waste takes place through the capillaries between blood and tissues. The network of capillaries joins the arteries with the veins. This blood capillary system was discovered by Marcello Malpighi.
Angiology is the study of the blood vascular system or the circulatory system. William Harvey is regarded as the father of angiology. He was the first to discover the path of blood in double circuits in humans.
Einthoven is regarded as the father of electrocardiography. He won the Nobel Prize in 1924 for the discovery of Electrocardiograph (ECG). Electrocardiogram was first recorded in 1887 by Waller but ECG was studied in detail by Einthoven in 1903.
Karl Landsteiner is known as the father of blood grouping. For the first time, he reported ABO blood groups in humans. He is the discoverer of A, B and O blood groups while the AB blood group was discovered by de Castello and Steini.