Donnan effect is shown by

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 organ that acts as a filter for blood is:

Which of the following figures correctly represents the path of a closed circulatory system?

Which of the following cardiac effects can be observed if the potassium concentration is increased two to three times the normal value?

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.