**Core Concept**
The superior rectus muscle is one of the six extraocular muscles responsible for controlling eye movement. It plays a crucial role in elevating the eyeball, particularly when the eye is adducted (moved towards the midline of the body).

**Why the Correct Answer is Right**
The superior rectus muscle achieves its primary action through its tendinous insertion on the superior and lateral part of the eyeball. As it contracts, it pulls the eyeball upward, thereby elevating the eye. This action is particularly important for maintaining binocular vision and preventing diplopia (double vision). The superior rectus muscle also has a secondary action of adduction, which helps to rotate the eyeball medially.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the inferior oblique muscle is primarily responsible for extorsion (rotating the top of the eyeball away from the nose) and elevation of the eyeball when it is adducted.
**Option B:** This option is incorrect because the superior oblique muscle is primarily responsible for intorsion (rotating the top of the eyeball towards the nose) and depression of the eyeball when it is adducted.
**Option C:** This option is incorrect because the medial rectus muscle is primarily responsible for adduction of the eyeball, and it does not have a significant role in elevation.
**Option D:** This option is incorrect because the lateral rectus muscle is primarily responsible for abduction of the eyeball, and it does not have a significant role in elevation.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the superior rectus muscle has a unique insertion on the superior and lateral part of the eyeball, which allows it to elevate the eye effectively. This understanding is crucial for diagnosing and managing conditions that affect the extraocular muscles, such as thyroid ophthalmopathy.

**Correct Answer: A. Elevates the eyeball.**