**Core Concept**
The question involves calculating the diameter at a certain point (D3) for a file with a given taper and initial diameter (D0). This is relevant to **endodontic instrumentation**, where files with specific tapers are used to shape root canals.

**Why the Correct Answer is Right**
To calculate D3 for a file, we use the formula related to the file's taper. The taper is given as 2%, which means the diameter increases by 2% per millimeter. Given D0 = 0.1 mm, we apply the formula considering the taper to find D3.

**Why Each Wrong Option is Incorrect**
**Option A:** This would be incorrect because it doesn't account for the taper correctly.
**Option B:** Similarly, this option might misapply the taper or initial diameter in the calculation.
**Option C:** This option is also incorrect as it likely misinterprets the formula or the given values.

**Clinical Pearl / High-Yield Fact**
Remember, the taper of an endodontic file is crucial for its design and function, affecting how the file cuts and the shape it produces in the canal. A 2% taper means the diameter increases by 0.02 mm per millimeter of length.

**Correct Answer:** D. 0.16 mm