**Core Concept**
The resolution of a light microscope refers to its ability to distinguish between two closely spaced objects. It is limited by the wavelength of light and the numerical aperture of the objective lens. The resolution is typically measured in micrometers (μm) and is a critical factor in determining the microscope's ability to visualize fine details in biological samples.

**Why the Correct Answer is Right**
The resolution of a light microscope is approximately 200-250 nanometers (nm), which is equivalent to 0.2-0.25 μm. This is due to the diffraction limit, which is caused by the spreading of light around the edges of the aperture in the objective lens. The diffraction limit is inversely proportional to the numerical aperture of the lens, and it is also influenced by the wavelength of the light used. In general, shorter wavelengths (such as ultraviolet or blue light) can provide higher resolution than longer wavelengths (such as red or infrared light).

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely incorrect, as the resolution of a light microscope is not typically measured in millimeters (mm) or centimeters (cm). While some microscopes may have a resolution of around 1-2 μm, this is still much lower than the diffraction limit.
* **Option B:** This option may be tempting, as some high-resolution microscopes can achieve resolutions of around 100-150 nm. However, this is still below the theoretical diffraction limit, and it typically requires specialized techniques such as super-resolution microscopy.
* **Option D:** This option is likely incorrect, as the resolution of a light microscope is not typically measured in picometers (pm) or other extremely small units. While some techniques may be able to achieve resolutions of around 1-10 pm, this is still far below the diffraction limit.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the resolution of a light microscope is limited by the diffraction limit, which is a fundamental physical constraint. However, some techniques such as super-resolution microscopy can provide higher resolution by using specialized dyes or other methods to reduce the diffraction limit.

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