**Core Concept**
The question is testing the student's knowledge of pulp vitality testing and the effects of root fracture on pulp response. The underlying principle is the temporary loss of pulp vitality due to injury or inflammation, which can lead to a false-negative response to pulp vitality tests.

**Why the Correct Answer is Right**
A root fracture can cause damage to the pulp, leading to inflammation and a temporary loss of vitality. This can result in a negative response to pulp vitality tests, such as thermal or electrical testing, for a period of time. The duration of this period can vary depending on the severity of the fracture and the body's healing response. The correct answer is based on the understanding that the pulp may take several weeks to recover from the injury and regain its normal vitality.

**Why Each Wrong Option is Incorrect**
* **Option A:** This is an incorrect answer as the duration of negative pulp vitality testing is typically longer than 2 weeks.
* **Option B:** This is an incorrect answer as the duration of negative pulp vitality testing is typically longer than 4 weeks.
* **Option C:** This is an incorrect answer as the duration of negative pulp vitality testing is typically longer than 12 weeks.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that a negative response to pulp vitality tests does not necessarily indicate the need for extraction. A thorough examination and follow-up testing are necessary to determine the extent of the injury and the pulp's potential for recovery.

**Correct Answer:** **C**. 12 weeks