**Core Concept**
Benedict's test is a qualitative test used to detect the presence of reducing sugars in a solution. It relies on the principle of oxidation-reduction reactions, where the reducing sugar reacts with copper ions in the reagent to produce a color change.

**Why the Correct Answer is Right**
The correct answer is **blue**. In Benedict's test, reducing sugars such as glucose, fructose, and lactose react with the copper sulfate in the reagent to form a brick-red precipitate of copper oxide. However, if no reducing sugar is present, the copper sulfate remains in its blue form. This is because the copper ions have not been reduced to their cuprous oxide form, which is responsible for the brick-red color. The absence of a color change indicates that the solution does not contain reducing sugars.

**Why Each Wrong Option is Incorrect**
* **Option A:** This is not a valid answer, as the color change in Benedict's test is not associated with green.
* **Option B:** This is not correct, as the color change in Benedict's test is not associated with yellow.
* **Option C:** This is not correct, as the color change in Benedict's test is not associated with black.

**Clinical Pearl / High-Yield Fact**
Remember that Benedict's test is a qualitative test and should not be used to measure the exact concentration of reducing sugars in a solution. It is also important to note that some sugars, such as maltose and sucrose, may not give a positive result in Benedict's test even if they are present in the solution.

**Correct Answer:** . Blue