Kb is so for bases and hydroxide is the result of the bases, thus the answer cannot be “A” or “B”. The greater the hydrogen ion concentration there is, and or the lower the Ka value, the more acidic the acid is. A Ka value of 0 means that there is a 100 % dissociation of the acid and thus very acidic. In this case, since letter “A” does not have a Ka value very close to “0” unlike “D” that has the complete dissociation of the hydrogen ion (Ka = 0). Answer choice “D” is the correct answer.
