**Core Concept**
The diaphragm is a dome-shaped muscle that separates the chest cavity from the abdominal cavity and plays a crucial role in respiration. It is primarily innervated by the phrenic nerve, which arises from the cervical spine (C3-C5). The diaphragm's unique anatomy and innervation make it relatively resistant to neuromuscular blockade.

**Why the Correct Answer is Right**
The diaphragm is resistant to neuromuscular blockade due to its dual innervation. In addition to the phrenic nerve, the diaphragm also receives vagal innervation from the vagus nerve. This dual innervation provides a backup mechanism for diaphragmatic contraction, making it less susceptible to neuromuscular blockade. Furthermore, the diaphragm's motor end plates are relatively resistant to the effects of neuromuscular blockers, such as succinylcholine and rocuronium.

**Why Each Wrong Option is Incorrect**
**Option A:** The statement is incorrect because it is the diaphragm that is resistant to neuromuscular blockade, not another muscle. The question asks for the muscle that is most resistant, and the diaphragm is the correct answer.
**Option B:** The statement is incorrect because the ocular muscles are actually among the first to be affected by neuromuscular blockade, due to their small muscle mass and rapid onset of action.
**Option C:** The statement is incorrect because the adductor pollicis muscle is often used as an indicator of neuromuscular function, and it is typically one of the first muscles to be affected by neuromuscular blockade.
**Option D:** The statement is incorrect because the intercostal muscles are also susceptible to neuromuscular blockade, and their function is often impaired in patients receiving neuromuscular blockers.

**Clinical Pearl / High-Yield Fact**
The diaphragm's resistance to neuromuscular blockade is an important clinical consideration, as it allows patients to maintain some degree of respiratory function even in the presence of significant neuromuscular blockade. This is particularly relevant in patients undergoing surgery or receiving neuromuscular blockers for other medical conditions.

**✓ Correct Answer: A. Diaphragm**