Spraying of $DDT$ on crops produces pollution of ...

Which one of the following pairs is not correctly matched?

Consider the following statements about Ramesh Chandra Dagar's work in the field of organic farming:
$I.$ Ramesh Chandra Dagar's work includes bee-keeping,dairy management,water harvesting,composting,and agriculture in a chain of processes.
$II.$ In this process,there is no need to use chemical fertilisers for crops as cattle excreta is used as manure.
$III.$ Crop waste is used for making compost,which is used as natural fertilizer.
$IV.$ Compost generates natural gas,which is used for the energy needs of the farm.
Which of the statements given above are correct?

Choose the incorrect statement.

Which of the following are advantages of ecological sanitation?
$I.$ It is a practical,hygienic and efficient method of waste disposal
$II.$ It is cost effective
$III.$ Human excreta can be recycled into natural fertilisers,to replace chemical fertilisers

What is the biological concentration of $DDT$ in the body fat of Indian people?