What is the full form of $WHO$?

Hashimoto's disease is a/an...

Select the correct option to fill up the blanks.
$(i)$ Diseases which are easily transmitted from one person to another,are called $.....$ diseases.
$(ii)$ In human body,parasite of malaria initially multiplies within the $........$ and then attack the $......$
$(iii) ......$ is the yellowish fluid secreted by mother during the initial days of lactation.
$(iv) ......$ and $.......$ are the primary lymphoid organs.

An insect bite may result in inflammation of that spot. This is triggered by the alarm chemicals such as

The discovery of antibiotics is considered a significant achievement of which century?

What should be done to prevent mosquitoes from entering the house?