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: Biochemistry
The sigma (cr) subunit of prokaryotic RNA polymerase: 
Select and explain. 
A. Binds the antibiotic rifampicin, B. Is inhibited by a-amanitin, C. Specifically recognizes the promoter site, D. Is pa of the core enzyme
C: Specifically recognizes the promoter site
Answer: C: Specifically recognizes the promoter site 
Explanation: C i.e. Specifically recognizes the promoter site