The correct option is B A- Base, B- Acid
Phenolphthalein is a colourless laboratory indicator which is used to identify if a substance is an acid or a base. It gives pink colour in basic solutions and remains colourless in acidic solutions.
On adding phenolphthalein in solution B, it remains colourless. So, the solution B must be either neutral or acidic in nature. When phenolphthalein is added to solution A, it turns to pink colour so it must be basic in nature.
So, comparing the results with the options, we can say that the solution A is a base and solution B is an acid.