Which of the following is considered a petrochemical?

The correct answer is styrene, which is considered a petrochemical because it is derived from petroleum and is a key building block in the production of various plastics and resins. Styrene is derived from the hydrocarbon benzene, which is obtained from petroleum refining. This makes it an essential component in the production of polystyrene, a commonly used plastic material.

In contrast, urea is primarily produced from ammonia and carbon dioxide, mainly through the Haber process but is not derived from petroleum products. Ammonia, while crucial in the production of fertilizers, is synthesized from nitrogen and hydrogen, often using natural gas as a hydrogen source, not directly from crude oil or petroleum. Polyurethane is a polymer created from the reaction of a diisocyanate with a polyol and can be derived from both petrochemical and bio-based sources, but it incorporates a wider array of feedstocks and is not classified strictly as a petrochemical. Thus, styrene stands out as the clear petrochemical choice among the options given.