At 298 K, HA has a pKa = 5, and HB has a pKa = 11. Based on this data, which of the following statement(s) is(are) true?
a. B- is a stronger base than A-
b. A- is a stronger base than B-
c. The given data can be used to calculate pKb of B-
d. Both A- and B- are weak bases