Methyl orange became red in a solution. What is the correct conclusion about that solution?

Correct answer: The solution is acidic

Methyl orange is an acid-base indicator whose colour depends on the medium. It appears red in an acidic solution and changes through orange toward yellow as the medium becomes less acidic or basic. Since the observation is red, the solution is acidic, so option A is correct. A basic solution would produce yellow, while neutral and metallic are not supported by the indicator’s red colour.