**Core Concept**
The macula is a specialized region of the retina responsible for central vision, located near the optic disc but distinct from it. The relationship between the macula and the optic disc is crucial for understanding retinal anatomy and diagnosing various ophthalmological conditions.

**Why the Correct Answer is Right**
The correct distance between the macula and the optic disc is approximately 3.5 to 4.0 mm. This measurement is essential for diagnosing conditions such as macular edema, where the macula is affected, or optic disc drusen, where the optic disc is abnormal. The distance is measured using fundus photography or optical coherence tomography (OCT) scans. The precise measurement helps clinicians assess the severity of the condition and plan appropriate treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a distance and is therefore ambiguous.
**Option B:** This option is incorrect because it does not correspond to the established measurement of 3.5 to 4.0 mm.
**Option C:** This option is incorrect because it is not a valid measurement in this context.

**Clinical Pearl / High-Yield Fact**
The distance between the macula and the optic disc is a critical measurement in ophthalmology, and clinicians should be familiar with the normal range to diagnose and manage various retinal conditions.

**Correct Answer:** D. 3.5 to 4.0 mm