Consider the formula F = \dfrac{N\cdot M}{P}F= P N⋅M F, equals, start fraction, N, dot, M, divided by, P, end fraction, where FFF represents the fertility of soil, NNN represents the amount of nutrients in the soil, MMM represents the amount of moisture in the soil, and PPP represents the amount of pollutants in the soil. Select an appropriate measurement unit for fertility of soil. Choose 1