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
Compared with autoclave, use of a dry heat oven for sterilization has the following disadvantage: 
Select and explain. 
A. Time-consuming, B. Less effective, C. Causes instruments to rust, D. Causes sharp instruments to dull
A: Time-consuming
Answer: A: Time-consuming 
Explanation: None