In a scientific investigation to determine if an unknown substance is starch, the correct option regarding how an indicator can help is:
A. The indicator will change the color of the substance.
For example, when iodine is used as an indicator for starch, it changes color from brown to blue-black when it comes into contact with starch. This color change indicates the presence of starch in the unknown substance. Options B and C do not accurately describe the role of indicators in this context.