**Core Concept**
Microbiological waste, which includes cultures, stocks, and other infectious materials, requires proper segregation and disposal to prevent the spread of pathogens. This is in accordance with biosafety guidelines and regulations to ensure the safety of laboratory personnel and the environment.

**Why the Correct Answer is Right**
The correct segregation of microbiological waste in yellow bags is to signify its biohazardous content. This color coding is a universal standard in laboratories to alert workers to the potential risks associated with handling such materials. Yellow bags are specifically designed to contain and dispose of biohazardous waste, including cultures, stocks, and other infectious materials, which are typically autoclaved before disposal.

**Why Each Wrong Option is Incorrect**
**Option B:** Red bags are used for disposing of anatomical and pathological waste, not microbiological waste. Anatomical waste includes tissues, organs, and body parts, which require special handling and disposal due to their infectious potential.

**Option C:** Blue bags are used for disposing of infectious sharps, such as needles and syringes, which pose a risk of puncture wounds and infection. These materials require special handling and disposal to prevent needlestick injuries.

**Option D:** Black bags are used for disposing of non-infectious, non-recyclable waste, such as paper, cardboard, and plastics. These materials do not pose a biohazard risk and can be disposed of in regular trash.

**Clinical Pearl / High-Yield Fact**
Remember the color coding system for waste disposal in laboratories: yellow for microbiological waste, red for anatomical and pathological waste, blue for infectious sharps, and black for non-infectious, non-recyclable waste.

✓ Correct Answer: A. Yellow.