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
Miriam, a college student with acute rhinitis sees the campus nurse because of excessive nasal drainage. The nurse asks the patient about the colour of the drainage. In acute rhinitis, nasal drainage normally is: 
Select and explain. 
A. Yellow, B. Green, C. Clear, D. Gray
C: Clear
Answer: C: Clear 
Explanation: Normally, nasal drainage in acute rhinitis is clear.
Yellow or green drainage indicates the spread of the infection to the sinuses. 
Gray drainage may indicate a secondary infection.