This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Quellung reaction is associated with 
Select and explain. 
A. Capsular degeneration, B. Capsular delineation, C. Capsular absence, D. Lecithinase production
B: Capsular delineation
Answer: B: Capsular delineation 
Explanation: Quellung reaction: a specific test of Streptococcus pneumoniae. A suspension of Streptococcus pneumoniae is mixed with a drop of the type-specific antiserum and a spoonful of methylene blue solution. In the presence of the homologous antiserum, the capsule becomes apparently swollen, sharply delineated and refractile. The Quellung test can be done directly with sputum from acute pneumonia cases. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 225