Identify the option that is NOT an elastomer among the following common materials.

Introduction / Context:
Elastomers are polymers capable of large, reversible deformations. The list provided includes well-known elastomer families used across seals, hoses, adhesives, and consumer goods.

Given Data / Assumptions:

• Polyisoprene = natural rubber analogue.
• Neoprene = polychloroprene elastomer.
• NBR = nitrile rubber, oil-resistant elastomer.
• Silicone rubber (VMQ) = high-temperature elastomer.

Concept / Approach:
Since all listed specific materials are elastomers, the only correct choice to the prompt “Which is not an elastomer?” is “None of these,” meaning each named material is, in fact, an elastomer.

Step-by-Step Solution:
Check each named polymer family for elastomeric usage and properties.Confirm all are elastomers in standard applications.Choose “None of these.”

Verification / Alternative check:
Materials handbooks list all four as elastomer classes with characteristic property profiles.

Why Other Options Are Wrong:
Each of (a), (b), (c), and (e) is an established elastomer; therefore they cannot be the correct “not an elastomer.”

Common Pitfalls:
Confusing “neoprene” as a trade name for wetsuits rather than the polymer family; it is an elastomer (polychloroprene).

Final Answer:
None of these