Which of the following weak acid–conjugate base pairs would buffer most effectively at pH 5.2?
A. hypobromous acid (Ka = 2.8 × 10–9) and its conjugate base
B. boric acid (Ka = 5.8 × 10–10) and its conjugate base
C. iodic acid (Ka = 1.7 × 10–1) and its conjugate base
D. chloroacetic acid (Ka = 1.4 × 10–3) and its conjugate base
E. acetic acid (Ka = 1.8 × 10–5) and its conjugate base