Solve the Problem $3.98 \times 10 ^ { - 5 }$

Solve the problem.
-The pH of a solution ranges from 0 to 14. An acid has a pH less than 7. Pure water is neutral and has a pH of 7. The pH of a solution is given by pH = - log x where x represents the concentration of the hydrogen ions in the
Solution in moles per liter. Find the hydrogen ion concentration if the pH = 4.4.

A) $3.98 \times 10 ^ { - 5 }$
B) $2.51 \times 10 ^ { - 4 }$
C) $2.51 \times 10 ^ { - 5 }$
D) $3.98 \times 10 ^ { - 4 }$