The diagram illustrates how pH changes as a strong alkali is added to a weak acid. $40\,\text{cm}^3$ of a strong alkali is introduced into a weak acid, and a sample of the resulting solution is then tested separately using methyl orange and thymolphthalein. Which row is correct?
- Amethyl orange: red; thymolphthalein: colourless
- Bmethyl orange: yellow; thymolphthalein: colourless
- Cmethyl orange: red; thymolphthalein: blue
- Dmethyl orange: yellow; thymolphthalein: blue