**Core Concept**
The magnification obtained with a direct ophthalmoscope is a function of its optical design, which involves a combination of lenses and mirrors to produce a highly magnified image of the retina. In a direct ophthalmoscope, the objective lens collects light from the posterior segment, and the eyepiece lens further magnifies the image for the examiner.

**Why the Correct Answer is Right**
The correct answer is determined by the optical principles involved in the design of the direct ophthalmoscope. The magnification is achieved through the combination of the objective lens and the eyepiece lens. The objective lens collects light from the retina, and the eyepiece lens further magnifies the image, resulting in a highly magnified view of the retina. This allows the examiner to visualize the retinal structures in detail.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely incorrect as it does not take into account the optical principles involved in the design of the direct ophthalmoscope.
* **Option B:** This option is incorrect as it suggests that the magnification is solely dependent on the objective lens, whereas the eyepiece lens also plays a crucial role in magnifying the image.
* **Option C:** This option is incorrect as it suggests a type of magnification that is not characteristic of a direct ophthalmoscope.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the direct ophthalmoscope provides a highly magnified view of the retina, but it has a limited field of view. This can make it challenging to examine the peripheral retina, which is why indirect ophthalmoscopy is often used in conjunction with direct ophthalmoscopy.

**Correct Answer: B. 20-30 times**