Cadmium Is a Toxic Heavy Metal $\times$ 10^-8 M $~~~~~~~~$ E ^$\circ$ = +0

Cadmium is a toxic heavy metal. The U.S. Environmental Protection Agency limits the concentration of cadmium ions in drinking water to less than 4 $\times$ 10^-8 M. Assess the feasibility of monitoring of cadmium in drinking water using a voltaic cell based on the following half-reactions.

$~~~~~~~~$ E ^$\circ$ = +0.7996 V $~~~~~~~~$ E ^$\circ$ = -0.4030 V

If the silver ion concentration were 0.100 M, what cadmium ion concentration at 298 K would increase the cell potential by 10 mV from the standard cell potential?

A) 3.6 $\times$ 10^-2 M
B) 4.6 $\times$ 10^-2 M
C) 4.6 $\times$ 10^-3 M
D) 6.8 $\times$ 10^-3 M
E) 6.8 $\times$ 10^-2 M