What type of response does the nerve agent Sarin trigger?

Sarin, a potent nerve agent, inhibits the enzyme acetylcholinesterase, leading to an accumulation of the neurotransmitter acetylcholine in the synaptic clefts. This results in an overstimulation of the cholinergic receptors and a massive cholinergic parasympathetic response. The parasympathetic nervous system is responsible for 'rest and digest' activities, and its excessive activation can lead to symptoms such as bronchoconstriction, increased salivation, lacrimation, urination, diarrhea, gastrointestinal distress, and cardiovascular effects like bradycardia and hypotension. The dramatic buildup of acetylcholine effectively overwhelms the body’s systems, producing a life-threatening scenario that necessitates immediate medical intervention.

The other options do not accurately represent the physiological effects of Sarin. A stimulatory sympathetic response does not align with the cholinergic effects, and there is no evidence of severe allergic reactions or immediate vasoconstriction triggered specifically by Sarin. Instead, the key features of exposure to Sarin are related to excessive cholinergic activity.