Among the following temperatures, the highest is

Among the given temperature we have to evaluate highest temperature. Let us convert the given temperatures in to same scale 

$$\begin{gathered} i) 100K=100-{273}^{0}C=-{173}^{0}C \\ ii) -{13}^{0}F \\ C=\frac{5}{9}(-13-32)=\frac{5}{9}\times -45=-{25}^{0}C \\ iii) -{20}^{0}C \\ iv) -{23}^{0}C \\ we can have -{20}^{0}C is highest among the given temperatures. \end{gathered}$$