Which of the following negative effects of anaphylaxis will be the most rapidly fatal if not treated immediately?
1 diffuse urticaria
2 severe hypotension
3 upper airway swelling
4 systemic vasodilation

2 severe hypotension  

3 upper airway swelling

Explanation:

Symptoms related to anaphylaxis have several factors and may occur alone or in various combinations involving the respiratory, neurological, cardiovascular, skin and gastrointestinal systems. The fatal outcome is related to circulatory collapse and / or respiratory failure.

Respiratory impairment may lead to upper airway obstruction by tongue, oropharynx or larynx angioedema; bronchospasm, chest tightness, cough, wheezing; rhinitis, sneezing, nasal congestion and rhinorrhea.

Cardiovascular impairment may lead to asthenia, hypotension, arrhythmia, hypovolemic shock, syncope, chest pain.

Both manifestations can lead to death quickly.

the answer is false, i know this answer is late but its for anyone else that needs it.