This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
What age group is the most susceptible to sepsis? 
Select and explain. 
A. Infants., B. Adolescents., C. Elderly, D. Young adults.
C: Elderly
Answer: C: Elderly 
Explanation: Elderly patients are at most risk for developing sepsis because of decreased physiologic reserves and an aging immune system.

Option A: Infants may have less physiologic reserves yet they have vaccines that strengthen their immune system than the elderly.
Option B: Adolescents may not have fully mature reserves yet they have a stronger immune system than the elderly.
Option D: Adolescents may not have fully mature reserves yet they have a stronger immune system than the elderly.