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: Dental
The organism least resistant to thermal inactivation is 
Select and explain. 
A. bacterial spores., B. virus., C. Streptococcus mutans., D. spirochete.
A: bacterial spores.
Answer: A: bacterial spores. 
Explanation: None