Answer: Subsistence agriculture.
Explanation: Subsistence agriculture is a type of farming in which farmers cultivate and grow food crops and livestocks to meet their needs and that of their family.
In this type of agriculture, farm products is aimed to survival and it doesn't involve use of large-scale irrigation, chemical fertilizer, or machinery and technology.
As we know that;
Density= mass/volume
By rearranging
Mass=. Density* volume
Mass=. 0.2*45
Mass=. 9 grams
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