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
The following are true of vibrio cholerae excepta) Produces indole and reduces nitratesb) Synthesises neuraminidasec) Dies rapidly at low temperatured) Vaccine confers long immunity 
Select and explain. 
A. ab, B. bc, C. cd, D. ac
C: cd
Answer: C: cd 
Explanation: None