**Core Concept**
The patient presents with a non-vital tooth due to a history of trauma, which is characterized by the obliteration of the root canal and a yellowish discoloration of the tooth. This is a classic presentation of a tooth that has undergone pulp necrosis, leading to a non-vital tooth.

**Why the Correct Answer is Right**
In a non-vital tooth, the primary goal of treatment is to eliminate the infection, alleviate symptoms, and restore the tooth's function and aesthetics. The obliteration of the root canal, as seen on radiograph, indicates that the pulp tissue has died and the canal has become canal-shaped and filled with tissue. In this case, the most appropriate treatment is to perform an **Endodontic therapy**, specifically a **Root Canal Treatment (RCT)**. This involves removing the infected pulp tissue, disinfecting the canal, and filling it with a biocompatible material to prevent further infection.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the treatment of a non-vital tooth with a history of trauma. Amalgam restorations are used for restoring teeth with extensive decay or fractures, but not for treating non-vital teeth.
* **Option B:** Orthodontic treatment may be considered for correcting the position of the tooth, but it is not the primary treatment for a non-vital tooth. The yellowish discoloration and obliteration of the root canal indicate an underlying infection, which requires endodontic treatment.
* **Option C:** This option may be considered for restoring the tooth's aesthetics, but it is not a treatment for the underlying infection. A dental crown may be placed after the endodontic treatment has been completed.

**Clinical Pearl / High-Yield Fact**
In cases of trauma, it's essential to consider the possibility of pulp necrosis, even if the tooth appears asymptomatic. A thorough radiographic examination and clinical evaluation are crucial in determining the best course of treatment.

**Correct Answer:** C.