The Concentration of Pollutants in a Stream Is Given By y=.06

Multiple Choice

The concentration of pollutants in a stream is given by $y=.06 e^{-3 x}$ , where $y$ is the amount of pollutant in grams per liter and $x$ is the distance, in kilometers, downstream from the source of the pollution. Match each question with one of the solutions A, B, C, or D.
-How far downstream is the pollutant level equal to $.02 \mathrm{gm} / \mathrm{L}$ ?

A) Solve $.02=.06 e^{-3 x}$
B) Solve $\frac{1}{2}(.06) =.06 e^{-3 x}$
C) Evaluate $.06 e^{-3(.02) }$
D) Evaluate $.06 e^{-3(1 / 2) }$