**Core Concept**
Non-septate hyphae with a tendency to branch at 90-degree angles are characteristic of a specific type of fungal infection, which is a critical diagnostic feature in clinical mycology. This distinctive morphological pattern is a key identifier for a particular genus of fungi that cause a life-threatening disease. The presence of non-septate hyphae, also known as broad, ribbon-like hyphae, is a hallmark of the pathogen in question.

**Why the Correct Answer is Right**
The correct answer is Mucormycosis, caused by fungi of the order Mucorales. These fungi, such as Rhizopus and Mucor, are characterized by their non-septate hyphae, which can be up to 20-30 micrometers in width. The 90-degree branching of these hyphae is a diagnostic feature that distinguishes them from other types of fungi. This unique morphology is due to the lack of septa, or divisions, within the hyphae, which allows them to grow and branch in a distinctive way. The presence of non-septate hyphae in tissue specimens is a critical diagnostic feature of Mucormycosis, which is a life-threatening disease that affects immunocompromised individuals.

**Why Each Wrong Option is Incorrect**
**Option B:** Aspergillosis is caused by fungi of the genus Aspergillus, which have septate hyphae that branch at 45-degree angles, not 90-degree angles. This distinctive branching pattern is a key identifier for Aspergillus species, which are common causes of opportunistic infections in immunocompromised patients.

**Option C:** Cryptococcus neoformans is a type of encapsulated yeast that causes cryptococcosis, not a disease characterized by non-septate hyphae. Cryptococcus neoformans is a significant pathogen in immunocompromised patients, particularly those with HIV/AIDS, but it does not cause Mucormycosis.

**Option D:** Coccidioides immitis is a type of dimorphic fungus that causes coccidioidomycosis, a disease characterized by the presence of spherules in tissue specimens, not non-septate hyphae. Coccidioides immitis is a significant pathogen in certain regions of the southwestern United States, but it does not cause Mucormycosis.

**Clinical Pearl / High-Yield Fact**
When diagnosing fungal infections, it's essential to examine the morphology of the organism, including the presence or absence of septa and the branching pattern of the hyphae. Non-septate hyphae with a tendency to branch at 90-degree angles are a distinctive feature of Mucormycosis, a life-threatening disease that requires prompt recognition and treatment.

**✓ Correct Answer: A. Mucormycosis**