Give below are four statement, a-d, regarding human blood circulatory system. Find the correct one.
(a) Arteries are thick-walled and have narrow lumen as compared to veins
(b) Angina is acute chest pain when the blood circulation to brain is reduced
(c ) Person with blood group AB can donate blood to any person with any blood group under ABO system
(d) Calcium ions play a very important role in blood clotting
A. a and b
B. a and d
C. b and c
D. c and d
