**Core Concept**
Sibson's fascia, also known as the suprapleural membrane, is a fibrous structure that forms the superior border of the thoracic cavity. It plays a crucial role in separating the thoracic cavity from the neck and facilitating the expansion of the lungs during respiration.

**Why the Correct Answer is Right**
The correct answer, **Option B: Arises from scalenus anterior**, is incorrect because Sibson's fascia actually arises from the transverse processes of the cervical vertebrae (C7) and the first thoracic vertebra (T1), not from the scalenus anterior muscle. The scalenus anterior muscle lies below Sibson's fascia and is not directly associated with its origin.

**Why Each Wrong Option is Incorrect**
**Option A:** Attached to cervical pleura. While Sibson's fascia is indeed related to the cervical pleura, it is not directly attached to it. Instead, it forms a separate layer that separates the thoracic cavity from the neck.
**Option C:** Subclavian arched over it. The subclavian artery and vein do indeed arch over Sibson's fascia, but this is not a defining characteristic of the fascia itself.
**Option D:** Attached to C7. This option is actually true, as Sibson's fascia is attached to the transverse process of the seventh cervical vertebra (C7).

**Clinical Pearl / High-Yield Fact**
To remember the origin of Sibson's fascia, use the mnemonic "CVT" (Cervical Vertebrae, Thoracic Vertebrae), which stands for the transverse processes of the cervical and thoracic vertebrae from which the fascia arises.

**✓ Correct Answer: B. Arises from scalenus anterior**