Sarah has a chest x-ray that shows she has tubercles in her lungs. What does that mean?

A. She had tuberculosis in the past but has recovered.

B. She has a dormant form of tuberculosis that could become active if her resistance is lower.

C. She has an active case of tuberculosis and is being treated with antibiotics.

D. She has a history of an infection that is similar to tuberculosis and therefore is immune to TB.