The Attempt at a Solution
I chose C as if a strong "something" is added to a weak "something" then you won't get a strong curve. So acetic acid will be eliminated. If D or E was added, the equivalence point should have pH of 7 or less. Therefore I chose C. Is this correct? As the type of base and molarity of it is not indicated, I assumed it was NaOH and 1 M.