Answer is (2) - blue.
Thymol blue is a pH indicator which 3 colors according to the pH.
Thymol blue shows red color at below pH than 1.2 and shows yellow color at the pH between 2.8 and 8.0. For the pH above 9.6, thymol blue shows blue color.
Hence, the thymol blue has 2 pH ranges as 1.2 - 2.8 and 8.0 - 9.6.
Since, pH = 11 is above the pH = 9.6, thymol blue shows blue color.
