**Core Concept**
Sabaroud's medium is a selective medium used in microbiology for the isolation and cultivation of certain types of microorganisms. It is an enriched nutrient agar that supports the growth of bacteria, particularly those that are difficult to culture.

**Why the Correct Answer is Right**
Sabaroud's medium is specifically designed to inhibit the growth of Gram-positive bacteria while allowing the growth of Gram-negative bacteria. This is achieved through the addition of bile salts, which are toxic to Gram-positive bacteria. The medium also contains peptones, which provide a source of nutrients for the bacteria. The selective action of Sabaroud's medium makes it an essential tool in the laboratory for isolating and identifying Gram-negative bacteria.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Sabaroud's medium is not typically used for the isolation of fungi. While it may support the growth of some fungal species, it is not a selective medium for fungi.
**Option B:** This option is incorrect because Sabaroud's medium is not used for the cultivation of anaerobic bacteria. While it can support the growth of some anaerobic bacteria, it is not a medium specifically designed for their isolation.
**Option C:** This option is incorrect because Sabaroud's medium is not used for the isolation of Mycobacterium species. These bacteria require specialized media, such as Lowenstein-Jensen medium, for their isolation.

**Clinical Pearl / High-Yield Fact**
Sabaroud's medium is a classic example of a selective medium in microbiology, and its use is an essential skill for any microbiology laboratory. By understanding the principles behind its selective action, laboratory personnel can effectively isolate and identify Gram-negative bacteria.

**Correct Answer:** D.