A solution shows pH 11, but after adding much water its pH becomes 9. What does this correctly mean?

Correct answer: The solution became less basic but is still basic

On the usual school pH scale, values above 7 indicate basic solutions, while 7 is neutral. A pH of 11 therefore represents a basic solution. Adding water dilutes the hydroxide ions, reducing their concentration and moving the pH toward 7. Although the pH falls to 9, it remains above 7, so the solution is still basic but less strongly basic. Thus option A is correct; it has not become acidic or neutral.