**Core Concept**
The fixed appliance in orthodontics is a dental appliance that is cemented or bonded to the teeth and is used to correct malocclusions or straighten teeth. The force produced by the appliance is crucial in moving the teeth into their desired position.

**Why the Correct Answer is Right**
The major force producing part of the fixed appliance is the **archwire**. The archwire is a thin, flexible wire that is placed in the brackets of the appliance and is responsible for applying the necessary force to move the teeth. The force is generated by the **elastic deformation** of the archwire, which is then transmitted to the teeth through the brackets. This force is controlled by the orthodontist to achieve the desired tooth movement.

**Why Each Wrong Option is Incorrect**
* **Option A:** While the brackets are an essential part of the fixed appliance, they do not produce the major force. Instead, they act as a means to transmit the force from the archwire to the tooth.
* **Option B:** The bands are used to attach the appliance to the molars and are not responsible for producing the major force.
* **Option C:** The ligatures are used to hold the archwire in place and do not produce the major force.

**Clinical Pearl / High-Yield Fact**
Remember that the force produced by the fixed appliance must be carefully controlled to achieve the desired tooth movement without causing damage to the surrounding tissues.

**Correct Answer:** C. Bands.