Which test can be used to detect the amount of antibodies in serum at the nanogram level?

In which of the following sets are all organisms considered vectors?

$VCRC$ stands for:

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.

Which factors are necessary in achieving good health?

$NMEP$ stands for