**Core Concept**
Rothera's test is a chemical assay used to detect the presence of reducing sugars, such as glucose, in a sample. This test is based on the reaction between the reducing sugar and a reagent containing nitroprusside, which results in the formation of a purple-colored complex.

**Why the Correct Answer is Right**
The correct answer is related to the detection of reducing sugars, which are a class of sugars that can donate electrons to other molecules. In Rothera's test, the reducing sugar reacts with the nitroprusside reagent to form a purple-colored complex due to the formation of a Schiff base. This reaction is specific to reducing sugars and is not observed with non-reducing sugars.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Rothera's test is not used for detecting non-reducing sugars, such as sucrose. Non-reducing sugars do not react with the nitroprusside reagent to form a purple-colored complex.
**Option B:** This option is incorrect because Rothera's test is not used for detecting ketones, such as acetone or acetoacetic acid. Ketones do not react with the nitroprusside reagent to form a purple-colored complex.
**Option C:** This option is incorrect because Rothera's test is not used for detecting amino acids, such as glycine or alanine. Amino acids do not react with the nitroprusside reagent to form a purple-colored complex.

**Clinical Pearl / High-Yield Fact**
Rothera's test is a simple and sensitive method for detecting reducing sugars in a sample, and it is often used in clinical settings to diagnose conditions such as diabetes mellitus. However, it is essential to note that Rothera's test is not specific for glucose and can also detect other reducing sugars.

**Correct Answer:** D.