A ammeter of resistance $$ R_m $$ is placed an arrangement as shown in the figure. Material of $$ R_m, R_{sh} $$ is copper whereas that of $$ R_s, R_x $$ is manganin. The condition for which the meter performance is compensated against temperature, is

A

$$ \frac {1}{R_m} + \frac {1}{R_{sh}} = \frac {1}{R_s} + \frac {1}{R_x} $$

B

$$ R_m R_s = R_{sh} R_x $$

C

$$ R_m + R_s = R_{sh} + R_x $$

D

$$ \frac {R_m}{R_s} + \frac {R_{sh}} {R_s} $$