Which of the following would tell you that a weak base is present? A. If the pH of the solution is close to 14.
B. If the solution is a good conductor of electricity.
C. An indicator added to the solution turns green-blue.
D. If there is a high reaction rate.

An indicator added to the solution turns green-blue.

Explanation:

An indicator is a substance which shows the degree of acidity or alkalinity of a solution by change in colour of the solution.

The universal indicator changes colour as the pH of the solution changes. Looking at the colour ranges for the universal indicator, the green-blue colour indicates a weak base.

not clear

it's all four options.