**Core Concept**
Myasthenia gravis is an autoimmune disease characterized by the production of antibodies against acetylcholine receptors (AChR) at the neuromuscular junction, leading to muscle weakness and fatigue. The disease can be exacerbated by medications that either compete with acetylcholine for receptor binding or alter the neuromuscular transmission in other ways.

**Why the Correct Answer is Right**
The correct answer is the drug that does not interfere with neuromuscular transmission or compete with acetylcholine for receptor binding. This is crucial in managing Myasthenia gravis, as the goal is to avoid exacerbating the disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** This drug is a non-depolarizing neuromuscular blocker that competes with acetylcholine for receptor binding, thereby exacerbating Myasthenia gravis. It works by blocking the nicotinic acetylcholine receptors at the neuromuscular junction.
* **Option B:** This drug is a depolarizing neuromuscular blocker that also competes with acetylcholine for receptor binding, but in a different way. It acts by activating the nicotinic acetylcholine receptors at the neuromuscular junction, leading to depolarization and muscle paralysis.
* **Option D:** This drug is a beta-2 adrenergic agonist that can worsen Myasthenia gravis by increasing the release of acetylcholine from nerve terminals and increasing the sensitivity of muscle cells to acetylcholine, thereby increasing the severity of muscle weakness.

**Clinical Pearl / High-Yield Fact**
In patients with Myasthenia gravis, it is essential to avoid medications that can exacerbate the disease, such as non-depolarizing neuromuscular blockers, depolarizing neuromuscular blockers, and beta-2 adrenergic agonists. Always consider the potential impact of medications on neuromuscular transmission when managing patients with this condition.

**Correct Answer:** D.