If the ph of a solution is decreased from 9 to 8, it means that the select one:
a. concentration of h+ has increased tenfold (10x) compared to what it was at ph 9.
b. concentration of h+ has decreased to one-tenth (1/10) what it was at ph 9.
c. the concentration of both oh- and h+ increased tenfold (10x) compared to what they were at ph 9
d. concentration of oh- has increased tenfold (10x) compared to what it was at ph 9.