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
Which of the following material is highly resistant to flexure and fractures suddenly when stressed? 
Select and explain. 
A. ZOE impression paste​, B. Impression plaster​, C. Impression compound​, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: The set impression materials can be rigid (inelastic) or elastic. A set rigid material is highly resistant to flexure, and it fractures suddenly when stressed, in a manner similar to that of chalk. Material is not flexible and will fracture when deformed, like chalk. ZOE impression paste, impression plaster, and impression compound are inelastic impression materials. The term elastic means that the material is flexible and can be deformed and still return to its original form when unstressed. Examples include agar, alginate, and elastomers.