**Core Concept**
The full choke shotgun is designed to produce a tight pattern of pellets at close range, which spreads out over longer distances due to the effects of air resistance and pellet dispersion. This phenomenon is known as "shot stringing" or "shot scatter."

**Why the Correct Answer is Right**
At 30 meters, the pellets fired from a full choke shotgun will have spread out significantly due to air resistance and the irregular shape of the pellets. As a result, the expected area of spread can be estimated using the "minute of angle" (MOA) method, which takes into account the barrel length, choke type, and the type of shot used. For a full choke shotgun, the expected area of spread at 30 meters is approximately 3-4 meters in diameter.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is too small, as the pellets would not have had enough time to spread out significantly at 30 meters.
* **Option B:** This option is too large, as the pellets would have had some time to spread out, but not to this extent.
* **Option D:** This option is not a realistic estimate of the area of spread, as it is much larger than expected.

**Clinical Pearl / High-Yield Fact**
When dealing with shotgun wounds, it's essential to consider the type of choke used, the distance from the victim to the shooter, and the type of shot used. This information can help you estimate the expected area of spread and the potential number of pellets that may have struck the victim.

**Correct Answer: C. 3-4 meters in diameter.**