NT Inc has registered an impressive $40\%$ sales growth for the just concluded calendar year $2019$ and expects to repeat this for $2020.$ Therefore, $($S$=$Sales$)$

Growth Rate for $2020=\frac{S_{2019}-S_{2018}}{S_{2019}}=40\%$

Growth Rate for $2020=\frac{S_{2020}-S_{2019}}{S_{2019}}=40\%$

Growth Rate for $2020=\frac{S_{2019}-S_{2018}}{S_{2018}}=40\%$

All the other $4$ answers are correct.

Growth Rate for $2020=\frac{S_{2020}-S_{2019}}{S_{2018}}=40\%$