Chelsea Has Been Sick Often in the Past Year, and When

Chelsea has been sick often in the past year, and when she finally starts to recover she gets sick again.She also has a very stressful work and family life.What is most likely the cause of Chelsea's constant illness?

A) She is too busy to see a doctor.
B) She has increased oxytocin levels due to chronic stress.
C) She has decreased lymphocyte production due to chronic stress.
D) She experiences understimulation of the sympathetic nervous system due to chronic stress.