Which from following polymers is grouped under elastomers?

Buna-S is a synthetic elastomer, also known as styrene-butadiene rubber (SBR). It has rubber-like properties and can stretch and return to its original shape, making it an elastomer. Here's a quick breakdown of the other options: - (B) Nylon 6,6: This is a nylon polymer, a type of polyamide used for fibers and engineering plastics, not an elastomer. - (C) Terylene: Also known as polyethylene terephthalate (PET), it is a thermoplastic used in fibers and films, not an elastomer. - (D) Polythene: Also called polyethylene, it's a thermoplastic polymer used in packaging, containers, etc., but not an elastomer.