Final answer:
Container B, which turned green when red cabbage juice was added, holds the base solution. Container A, turning bright pink, indicates an acidic solution.
Step-by-step explanation:
The student is asking a question related to acid-base indicators. Red cabbage juice contains a natural pH indicator that changes color depending on the acidity or basicity of the solution it is mixed with. When red cabbage juice is added to container A and it turns bright pink, it indicates that container A holds an acidic solution. Conversely, when container B turns green upon the addition of red cabbage juice, it means container B contains a base solution. This is because red cabbage juice turns colors like pink in acidic environments and green to yellow in basic environments.