**Core Concept:**
The core concept in this question is the relationship between traumatic dental injuries, pulp testing results, and treatment options for an injured tooth. Pulp testing assesses the vitality of a tooth's pulp (nerve tissue) after a traumatic injury. In this context, a negative (non-reactive) pulp test indicates that the pulp is still alive, suggesting that the injury is limited to the tooth's outer structure (enamel, dentin) rather than affecting the pulp directly.

**Why the Correct Answer is Right:**
In this scenario, the correct answer is **D** because it addresses the traumatic injury to the tooth without causing further damage to the pulp. Root canal therapy involves cleaning, disinfecting, and shaping the root canals of the tooth, followed by filling and sealing them to prevent infection. Since the pulp testing is negative, there is no need to treat the pulp at this stage, and the tooth's outer structures (enamel, dentin) are intact.

**Why Each Wrong Option is Incorrect:**

**A:** Extraction (removal of the tooth) is not the correct choice as it does not address the injured tooth and does not preserve tooth structure. Additionally, the traumatic injury has already occurred, so extracting the tooth would not prevent further complications or restore function.

**B:** Occlusal (bite) adjustment would not address the traumatic dental injury to the tooth, nor would it preserve tooth structure. This option focuses on bite issues rather than the primary concern of the injured tooth.

**C:** Tooth-colored restoration (fillings, inlays, onlays) is not the correct choice when the tooth has already sustained an injury. This option focuses on restorative treatment rather than addressing the traumatic injury and preserving tooth structure.

**Clinical Pearl:**

In clinical practice, this question highlights the importance of considering the full range of treatment options when faced with traumatic dental injuries. To maintain tooth structure and prevent further complications, the appropriate treatment depends on the severity and extent of the injury. For minor injuries, conservative treatments (e.g., pulpectomy, pulpotomy, or restorative treatments) may suffice. However, when the pulp is at risk or has been compromised, more extensive treatments, such as root canal therapy (as described in option D), are necessary to preserve the tooth and prevent potential complications like abscesses or pain.