The Standard Cell Potential (E°)of a Voltaic Cell Constructed Using $\quad$

The standard cell potential (E°) of a voltaic cell constructed using the cell reaction below is 0.76 V:
$\quad$ Zn(s) + $2 \mathrm { H } ^ { + }$ (aq) ? $\mathrm { Zn } ^ { 2 + }$ (aq) + $\mathrm { H } _ { 2 }$ (g)
With $\mathrm { P } _ { \mathrm { H } _ { 2 } }$ = 1.0 atm and [ $\mathrm { Zn } ^ { 2 + }$ ] = 1.0 mol L^-1,the cell potential is 0.45 V.The concentration of $\mathrm { H } ^ { + }$ in the cathode compartment is ________ mol L^-1.

A) 3.3 × 10^-11
B) 2.4 × 10^-3
C) 1.1 × 10^-21
D) 0.73
E) 5.8 × 10^-6