It would be the last choice. <span>They are stored for later use.</span>
The correct answer is letter C.
Explanation: A simple and inexpensive way to improve soil fertility is by installing green manure or mulching, which adds organic materials and nitrogen to the soil, increases biological activity and recovers leached (washed) nutrients to the deepest layers.
<span>Werner von Siemens (none of the others were industrialists)
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C is the correct answer, it kinda sucks that they require 20 character answers
