Litmus paper that is blue will turn/stay _____ in the presence of a strong base.

Litmus paper that is blue will remain blue in the presence of a strong base because blue litmus paper is specifically designed to indicate a basic environment. When it comes in contact with a basic solution, there is no change in color, as blue litmus paper is already the color associated with alkaline conditions.

In contrast, red litmus paper would turn blue in a basic solution, indicating a pH shift toward more alkalinity. The other potential color changes indicated by the choices do not occur with blue litmus paper in a strong basic setting. Therefore, the answer reflects the stable nature of blue litmus in alkaline environments.