**Core Concept**
Simple tongue thrust swallowing is a type of swallowing disorder characterized by the protrusion of the tongue beyond the anterior teeth during the swallowing process. This can lead to various dental and orthodontic issues. In simple tongue thrust swallowing, the tongue is placed too far forward in the mouth, causing the teeth to be pushed together.

**Why the Correct Answer is Right**
The correct answer, "Teeth apart swallow," is not a feature of simple tongue thrust swallowing because, in this condition, the tongue is placed too far forward, causing the teeth to be pushed together. This is in contrast to a normal, healthy swallow, where the tongue is placed behind the upper teeth and the lips seal over the teeth, keeping them apart. The contraction of facial muscles and mandibular elevators is necessary for proper tongue thrust swallowing, and an anterior open bite is a common result of this disorder.

**Why Each Wrong Option is Incorrect**
**Option A:** Contraction of facial muscle is actually a feature of simple tongue thrust swallowing, as it helps to propel the tongue forward.
**Option B:** Contraction of mandibular elevators is also a feature of simple tongue thrust swallowing, as it helps to elevate the mandible and facilitate the forward movement of the tongue.
**Option D:** An anterior open bite is actually a common result of simple tongue thrust swallowing, where the tongue's forward placement causes the upper and lower teeth to be separated.

**Clinical Pearl / High-Yield Fact**
A key feature of simple tongue thrust swallowing is the forward placement of the tongue, which can be identified by observing the patient's swallow or by taking a lateral cephalometric radiograph. This is a crucial aspect of diagnosis and treatment planning in orthodontics and oral surgery.

**✓ Correct Answer:** C. Teeth apart swallow