**Core Concept**
The patient's presentation of acute onset descending paralysis, quadriparesis, areflexia, and non-reactive pupils suggests a severe neurological disorder affecting the spinal cord and brainstem.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with a diagnosis of **Guillain-Barré Syndrome (GBS)**, an autoimmune disorder characterized by demyelination of the peripheral nerves. The history of preceding viral infection and the presence of non-reactive pupils, which is a red flag for autonomic dysfunction, further supports this diagnosis. The descending paralysis is due to the ascending damage to the peripheral nerves from the lower limbs to the upper limbs.

**Why Each Wrong Option is Incorrect**
**Option A:** **Myasthenia Gravis** typically presents with fluctuating weakness, particularly of the extraocular muscles, and often improves with rest. The patient's presentation of descending paralysis and non-reactive pupils is not typical for Myasthenia Gravis.
**Option B:** **Botulism** presents with descending paralysis, but the pupils are typically small and reactive, not non-reactive as seen in this patient.
**Option C:** **Amyotrophic Lateral Sclerosis (ALS)** is a progressive motor neuron disease, but it typically presents with a more insidious onset and upper motor neuron signs, not acute descending paralysis.

**Clinical Pearl / High-Yield Fact**
GBS can be preceded by a viral infection, such as Campylobacter jejuni, and is associated with increased risk of respiratory failure due to diaphragmatic weakness.

**Correct Answer: D. Guillain-Barré Syndrome**