Why should preventive measures and biological control methods be preferred for protecting crops?

Among the given options,which one is not correct for the use of large amount of fertilisers and pesticides?

Sid went to market to buy foodgrains for his home and on returning when his mother found the grains discoloured and of low and poor quality,she returned them back to the vendor. The vendor told Sid's mother that it was due to the storage loss of the grains that resulted in their poor quality and gave her the good quality grains.
$(a)$ What kind of qualities are shown by Sid's mother?
$(b)$ What could be the control measures to prevent this storage loss?

$(a)$ State two characteristics of a healthy animal.
$(b)$ State any four characteristics of storage structure for grains.

$(i)$ What are weeds? Give two examples.
$(ii)$ "Removal of weeds from cultivated fields during the early stages of growth of crops is essential for a good harvest." Justify the statement.
$(iii)$ List five preventive methods that help in weed control.

How is spraying different from fumigation?