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: Microbiology
Which of the following best denotes classical complement pathway activation in immunoinfiammatory condition - 
Select and explain. 
A. C
2
, C
4
, C
3
 decreased, B. C
2
 and C
4
 normal, C
3
 is decreased, C. C
3
 normal and C
2
 C
4
 decreased, D. C
2
, C
4
, C
3
 all are elevated
A: C
2
, C
4
, C
3
 decreased
Answer: A: C
2
, C
4
, C
3
 decreased 
Explanation: None