I would select A. Nitrogen due to the fact Nitrogen is found in most soil samples and Aluminum and mercury are metals. Also, limestone i don't find beneficial to plants whatsoever.
3x+4y=23
2y-x= -19/ multiply -2
4y + 3x = 23
-4y - 2x = 38
_______________
X = 61
2y - x = -19
2y - 61 = -19
2y = 61 -19
2y = 42
Y = 21
Answer:
Food
Explanation:
I mean what else would it be?