Continuing with the previous question, and given: You were…

Continuing with the previous question, and given: You were able to extract your product and your yield was 98% (exceptional) You still found trace carboxylic acid impurities (approx.1%, above your required standards) Which of the following would be the best method for removing the impurities? (Select the most effective method assuming a large scale reaction, repeating until purity achieved)