Which toxic substance is responsible for the chills and high fever recurring every three to four days in malaria?

In the sigmoid curve of growth, the alphabets indicate the sequence of events. Choose the correct option where the alphabet specifies the event.

Compare the life style of people living in the urban areas with those of rural areas and briefly describe how the life style affects their health.

$HIV$ decreases natural immunity of the body by

‘Cholera' is caused by

The immunoglobulin abundant in colostrums is