A gardener finds that the required fertilizer mass $y$, in units of $\text{kg}$, will vary directly with the garden area $A$, in units of $\text{m}{}^2$, and will vary inversely with the fertilizer concentration $c$, in units of $\frac{\text{kg}}{{\text{m}}^2}$ (for the recommended strength), such that $y=\frac{kA}{c}$. If the gardener uses 50 $\text{kg}$ of fertilizer for a 200 ${\text{m}}^2$ plot with a concentration of $c=2$, determine how many kilograms will be needed for a 300 ${\text{m}}^2$ plot at concentration of $c=3$.

• A. 50 kg
• B. 75 kg
• C. 100 kg
• D. 25 kg