**Core Concept**
Malignant otitis externa is a severe, necrotizing infection of the external auditory canal and temporal bone, typically affecting immunocompromised individuals. It is characterized by its potential to cause significant morbidity and mortality if left untreated.

**Why the Correct Answer is Right**
Severe hearing loss is not the chief presenting complaint of malignant otitis externa. Instead, patients often present with pain, fever, and otorrhea (discharge from the ear). The infection can spread to the temporal bone, causing facial paralysis, and potentially lead to severe complications, including osteomyelitis and cranial nerve involvement. The chief complaint is usually related to the pain and discomfort caused by the infection, rather than hearing loss.

**Why Each Wrong Option is Incorrect**
**Option A:** ESR (erythrocyte sedimentation rate) is indeed used for follow-up after treatment, as it can help monitor the resolution of the infection. However, it is not the most specific marker for malignant otitis externa.
**Option B:** Granulation tissue on the superior wall of the external auditory canal is indeed a characteristic finding of malignant otitis externa, making this statement true.
**Option D:** Pseudomonas aeruginosa is the most common causative organism of malignant otitis externa, especially in diabetic and immunocompromised patients.

**Clinical Pearl / High-Yield Fact**
Malignant otitis externa is a medical emergency that requires prompt treatment with broad-spectrum antibiotics, including coverage for Pseudomonas aeruginosa. Early recognition and treatment can prevent severe complications and improve outcomes.

**✓ Correct Answer: C. Severe hearing loss is the chief presenting complaint**