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
Incubation period for bacillus cereus -a) 1-6 hrsb) 8-16 hrsc) 24hrsd) > 24 hrs 
Select and explain. 
A. ac, B. bc, C. ad, D. ab
D: ab
Answer: D: ab 
Explanation: None