**Core Concept**
Karyotyping involves the analysis of the number and structure of chromosomes in a cell. The resolution of a light microscope is a critical factor in karyotyping, as it determines the level of detail that can be observed. In the context of chromosome visualization, resolution refers to the ability to distinguish between different bands or regions on a chromosome.

**Why the Correct Answer is Right**
The resolution of a light microscope is typically limited to around 200-250 nanometers (nm), which corresponds to option C. This is because light microscopes use visible light to illuminate the sample, and the wavelength of visible light is around 400-700 nanometers. As a result, the resolution of a light microscope is limited to around 200-250 nm, which is sufficient for observing the overall structure of chromosomes but not for resolving the fine details of chromosome bands. The correct resolution for karyotyping is typically achieved using banding techniques, such as G-banding, which can provide a resolution of around 1-5 megabases (Mb).

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is too high a resolution for a light microscope. While it is theoretically possible to achieve higher resolutions using advanced microscopy techniques, such as super-resolution microscopy, these methods are not typically used for karyotyping.
* **Option B:** This option is incorrect because it is too low a resolution for karyotyping. While light microscopes can resolve features as small as 200-250 nm, this is not sufficient for distinguishing between different chromosome bands.

**Clinical Pearl / High-Yield Fact**
When performing karyotyping, it is essential to use banding techniques to achieve a resolution of around 1-5 Mb. This allows for the accurate identification of chromosomal abnormalities, such as deletions or duplications.

**Correct Answer: C. 200-250 nm**