Acetic acid, CH₃COOH, has a pKa of 4.76. A buffer was created with acetic acid, CH₃COOH, and acetate, CH₃COO⁻. At what pH would it be considered effective? Select all that apply.
a) pH < 4.76
b) pH = 4.76
c) 4.76 < pH < 7
d) pH = 7
e) pH > 7