**Core Concept**
The question is testing knowledge of the cranial nerves involved in controlling the muscles of facial expression and the mechanism of sucking on a straw. The correct answer is related to the cranial nerve responsible for controlling the muscles of facial expression, particularly those involved in oral and pharyngeal functions.

**Why the Correct Answer is Right**
Sucking on a straw requires coordinated movement of the lips, tongue, and pharynx. This action is primarily facilitated by the trigeminal nerve (cranial nerve V), which controls the muscles of mastication and facial expression, including the buccinator and orbicularis oris muscles. However, the primary nerve responsible for controlling the muscles involved in sucking on a straw is the facial nerve (cranial nerve VII).

**Why Each Wrong Option is Incorrect**
**Option A:** The glossopharyngeal nerve (cranial nerve IX) is primarily involved in controlling the muscles of the pharynx and palate, but it is not directly responsible for the action of sucking on a straw.

**Option B:** The vagus nerve (cranial nerve X) is involved in controlling various functions, including swallowing and voice production, but it is not responsible for the specific action of sucking on a straw.

**Option C:** The hypoglossal nerve (cranial nerve XII) is responsible for controlling the muscles of the tongue, but it is not directly involved in the action of sucking on a straw.

**Clinical Pearl / High-Yield Fact**
A patient with a lesion of the facial nerve (cranial nerve VII) may exhibit inability to suck on a straw, as well as weakness of the muscles of facial expression, including the orbicularis oris muscle.

**Correct Answer: D. Facial nerve (cranial nerve VII)**