In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to treat a fungal infection of the sinus cavity [title] Track the progress of the fungus. [step] Aspergillus fungi will first infect the paranasal sinuses and airways. It may then progress down into the lung tissue, or remain in the sinuses. <sep> (A) If the infection continues into the lining of the mouth, it might result in nose bleeds and difficulty swallowing. [title] Examine the nasal cavity to get a sense of where the infection should originate. (B) It can also drip down the lung tissues. [title] Get your sample taken at a laboratory. (C) If you first suspect an infection, you should see your doctor. Other telltale signs of fungal infection in a sinus cavity are : [substeps] A decreased lung capacity that restricts oxygen flow to the throat. (D) At this time, the fungi will form a fungus ball, or aspergilloma, which is the hallmark of this infection. [substeps] A fungus ball is a mass of fungi that form together.
A:
D