Why did Þórdís Hrönn have to self-isolate four times during the COVID-19 pandemic?

A. She worked in a hospital and had to quarantine due to her job, and also had close contact with infected individuals
B. She was a close contact of a KR footballer who tested positive all four times
C. She had underlying health conditions that made her more susceptible to the virus
D. She traveled to high-risk areas during the pandemic
Answer: 