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: ENT
Which of the following are of viral origin -a) Laryngeal papillomab) Nasopharyngeal carcinomac) Vocal noduled) Laryngeal web 
Select and explain. 
A. ac, B. a, C. ab, D. bc
C: ab
Answer: C: ab 
Explanation: None