Temperature of cold junction in a thermo couple is $10^{\circ}$ and neutral temperature is $270^{\circ}$, then the temperature of inversion is

Question

$$\begin {array} {1 1} (a)\;540^{\circ}C & \quad (b)\;530^{\circ}C \\ (c)\;280^{\circ}C & \quad (d)\;260^{\circ}C \end {array}$$