Select the statements that correctly describe a buffer. a) An acid added to the buffer solution reacts with the weak base of the buffer. b) The pH of a buffer solution is determined by the ratio of the concentration of conjugate base to the concentration of strong acid. c) A buffer is generally made up of a weak acid and its conjugate base. d) The pH of a buffer solution does not change significantly when any amount of a strong acid is added. e) The Ka of a buffer does not change when any amount of an acid is added to the buffer solution.