**Core Concept**
Right lateral rectus palsy is a condition that affects the lateral rectus muscle, which is responsible for the abduction of the eye. This muscle is innervated by the abducens nerve (CN VI), and its dysfunction leads to a specific set of clinical findings.

**Why the Correct Answer is Right**
In right lateral rectus palsy, the primary clinical feature is the inability to abduct the right eye. This results in the eye deviating medially on attempted lateral gaze, a condition known as esotropia. The patient may also experience diplopia (double vision) due to the misalignment of the eyes. The medial rectus muscle, which is responsible for adduction, is usually overactive in an attempt to compensate for the weakness of the lateral rectus muscle.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because in right lateral rectus palsy, the patient will experience difficulty abducting the right eye, not adducting it.
* **Option B:** This option is incorrect because the medial rectus muscle is usually overactive in an attempt to compensate for the weakness of the lateral rectus muscle, not underactive.
* **Option D:** This option is incorrect because the patient will experience diplopia due to the misalignment of the eyes, not due to a lack of diplopia.

**Clinical Pearl / High-Yield Fact**
In cases of lateral rectus palsy, the patient may experience a significant reduction in the range of motion of the affected eye, particularly in abduction. This can be a useful clinical finding in differentiating lateral rectus palsy from other forms of strabismus.

**Correct Answer: A. Difficulty adducting the right eye.**