What Would Be the Concentration of Hydronium Ions in a Solution

What would be the concentration of hydronium ions in a solution that had a pH = -3? Why would such a solution be impossible to prepare?

A) Concentration of $\mathrm { H } _ { 3 }$ $\mathrm { O } ^ { + }$ = 3 M.It is impossible because it is hard to measure such a small amount of hydronium ions accurately.
B) Concentration of $\mathrm { H } _ { 3 }$ $\mathrm { O } ^ { + }$ = 30 M.It is impossible because pH can not be negative.
C) Concentration of $\mathrm { H } _ { 3 }$ $\mathrm { O } ^ { + }$ = $10 ^ { 30 }$ M.It is impossible because any container used to hold the acid would immediately corrode.
D) Concentration of $\mathrm { H } _ { 3 }$ $\mathrm { O } ^ { + }$ = $10 ^ { 3 }$