Which of the following cells phagocytose microorganisms rapidly?

Select the correct option:
$(1)$ $AB / O$ blood group is the universal recipient.
$(2)$ Mitral valve / Semilunar valve is located between the atrium and the ventricle.

Given below are four statements $(i-iv)$ regarding the human blood circulatory system.
$(i)$ Arteries are thick-walled and have a narrow lumen as compared to veins.
$(ii)$ Angina is acute chest pain when the blood circulation to the heart muscle is reduced.
$(iii)$ Persons with blood group $AB$ can donate blood to any person with any blood group under the $ABO$ system.
$(iv)$ Calcium ions play a very important role in blood clotting.
Which two of the above statements are correct?

Which of the following vertebrate organs receives only oxygenated blood?

All of the following are vasoconstrictor agents except:

Cords of Billroth are blood-filled spaces found in which of the following organs?