A solution gives red colour with universal indicator. After adding water the colour becomes yellow but not green. What is the correct conclusion?

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

Universal-indicator colours represent approximate pH ranges. Red shows strong acidity, while yellow represents a less strongly acidic range. Adding water dilutes the solution and lowers the hydrogen-ion concentration per unit volume, so the colour shifts toward green, which represents neutrality. Because the result is yellow rather than green, neutralisation has not been reached; the solution remains acidic. Thus option A is correct, while B, C, and D are inconsistent with the observation.