b. According to the theory on a pH scale, a more acidic substance is assigned a lower value. Normally substances with pH less than 7 are considered as acidic and those with pH greater than 7 are considered as basic with acidic strength increasing as we move towards 1 from 7 and the basic strength increases as we move toward 14 from 7. The more the acidic a substance is the more the hydrogen ions concentration will be.

Hence, in the given solutions, solution A has more hydrogen ions concentration as it is having the least pH value out of the three.

The nature of each solution is: -

Solution A – acidic

Solution B – basic

Solution C – basic