A solution turns blue litmus red but keeps phenolphthalein colourless. Which conclusion is correct?

Correct answer: The solution is acidic

Indicators provide the governing evidence about the solution’s acid-base nature. Blue litmus turns red in an acidic medium, while phenolphthalein remains colourless in acidic and neutral media and turns pink in a sufficiently basic medium. The two observations are therefore consistent with acidity. They do not prove that the solution contains no salt, and a solution is not itself metallic. Thus option A is the valid conclusion.