Which of the following substances can cause vasodilation?

What is the need for a circulatory system?

Which of the following is correct regarding blood coagulation?
$I$. Vitamin-$K$ is necessary for the formation of prothrombin.
$II$. Conversion of fibrinogen to fibrin is done by thrombin.
$III$. Conversion of prothrombin to thrombin is done by the enzyme complex prothrombinase.
The option with the correct combination is:

Which organ in an adult human causes the least damage if removed?

Oedema is defined as:

Match column $I$ with column $II$:

Column $I$	Column $II$
$(a)$ Eosinophils	$(i)$ Coagulation
$(b)$ $RBC$	$(ii)$ Universal Recipient
$(c)$ $AB$ Group	$(iii)$ Resist Infections
$(d)$ Platelets	$(iv)$ Contraction of Heart
$(e)$ Systole	$(v)$ Gas transport