Which of the following flowcharts correctly represents the process of blood clotting?

Consider the following four statements regarding the human circulatory system:
$(a)$ Arteries have thick walls and a narrower lumen compared to veins.
$(b)$ Angina is a sudden chest pain.
$(c)$ In the $ABO$ blood grouping system,a person with blood group $AB$ can donate blood to anyone.
$(d)$ Calcium ions play a significant role in blood clotting.
Which two of the above statements are correct?

The given figure shows the schematic plan of blood circulation in humans with labels $A$ to $D$. Identify the label and give its function/functions.

Which of the following cells phagocytose microorganisms rapidly?

Which of the following statements is correct?

The $.....$ is the blood bank of the body.