**Core Concept**
Trachoma is a bacterial eye infection caused by *Chlamydia trachomatis*, leading to blindness if untreated. Azithromycin prophylaxis is a key intervention in mass drug administration (MDA) programs under the WHO-recommended SAFE strategy, targeting areas with high disease prevalence to reduce transmission.

**Why the Correct Answer is Right**
Azithromycin prophylaxis is recommended for trachoma when the prevalence of trachoma in a community exceeds 10%, as defined by the WHO’s SAFE strategy. This threshold ensures that the intervention is applied in areas where active transmission is likely, maximizing public health impact. The 10% prevalence cutoff is based on epidemiological data showing that at this level, the risk of ongoing transmission is high, and mass treatment can significantly reduce disease burden.

**Why Each Wrong Option is Incorrect**
Option A: 8% – This is below the WHO-recommended threshold and not sufficient to justify mass azithromycin prophylaxis.
Option B: 6% – This is considered low prevalence; treatment is not indicated as transmission risk is minimal.
Option C: 4% – Below the threshold; no prophylaxis is recommended at this level.

**Clinical Pearl / High-Yield Fact**
The WHO recommends azithromycin for trachoma prophylaxis only when trachoma prevalence is ≥10% in a community. This is a key cutoff in public health programs and is often tested in exams on preventive medicine.

✓ Correct Answer: D. 10%