If soap has high alkali content it irritates skin. How can the amount of excess alkali be determined? What can be the source of excess alkali?

Options

1. AThe amount of excess alkali can be determined by taste.
2. BThe amount of excess alkali can be determined by the soap's color.
3. CAcid-base titration can be used to determine the excess amount of alkali in soap. The excess alkali left after
4. DThe source of excess alkali is usually natural oils in the soap.