**Core Concept**
Micrococci and Staphylococci are both gram-positive cocci, but they can be differentiated based on their catalase activity, hemolytic patterns, and growth characteristics. The ability to produce catalase is a key distinguishing feature between these two genera.

**Why the Correct Answer is Right**
The correct answer is based on the fact that Micrococci are catalase-positive, whereas Staphylococci are catalase-negative. This is because Micrococci contain the enzyme catalase, which catalyzes the breakdown of hydrogen peroxide into water and oxygen. This reaction is a key diagnostic feature, as it allows for the differentiation of Micrococci from Staphylococci. The catalase test is a simple and reliable method for identifying Micrococci.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe a method for differentiating Micrococci from Staphylococci.
**Option B:** This option is incorrect because it is a characteristic of Staphylococci, not Micrococci.
**Option C:** This option is incorrect because it is a characteristic of both Micrococci and Staphylococci.

**Clinical Pearl / High-Yield Fact**
When differentiating Micrococci from Staphylococci, it is essential to remember that Micrococci are catalase-positive and produce a golden-yellow pigment, while Staphylococci are catalase-negative and may produce a pink or red pigment on certain media.

**Correct Answer: A. Catalase test**