Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

Notes that plastics are widely used for packaging and carry bags — categories where LDPE is commonly employed.

A student could use this to check which polymers (e.g., polyethylene) are typically used for such items and then ask whether BPA is part of those polymer formulations.

Explains that plastics tend to concentrate organic compounds (PCBs, DDT, nonylphenols) from the environment, distinguishing between the bulk polymer and small organic contaminants or additives.

One could extend this to consider whether BPA is more likely to be an additive/contaminant that associates with plastics rather than a backbone monomer of common packaging polymers like LDPE.

Gives a practical classification of plastics used in packaging (rigid vs flexible vs multilayer), implying plastics are formulated differently for different uses and may contain different layers/additives.

Use this to guide a search for typical polymer types used in each category (e.g., LDPE for flexible films) and whether BPA is reported as a component in those formulations.

Calls attention to differences between biodegradable and non-biodegradable plastics, implying that polymer chemistry determines environmental behavior and composition.

A student could follow this hint to compare chemical structures of common non-biodegradable polymers (like polyethylene) with BPA's structure to judge whether BPA is a building block of such polymers.

Defines density and notes how it distinguishes materials; 'low-density' in LDPE is a descriptive property tied to polymer structure and packing.

Combine this basic definition with external knowledge that 'LDPE' denotes a polyethylene with specific molecular branching/density, and then ask whether BPA (a distinct small molecule) fits as a monomer forming that polymer.