If the cold junction of a thermo-couple is kept at $0^{\circ}C$ and the hot junction is kept at $T^{\circ}C$, then the relation between neutral temperature $(T_n)$ and temperature of inversion $(T_i)$ is:
( A ) $T_n = T_i/2$
( B ) $T_n = T_i - T$
( C ) $T_n = T_i + T$
( D ) $T_n = 2T_i$