In the plastics industry, which of the following is commonly involved?

High temperatures, oils, and solvents are commonly involved in the plastics industry due to the processes used in the melting and molding of plastic materials. During the manufacturing of plastics, high temperatures are required to melt the raw materials, such as resins, to allow them to be easily shaped into various products. Oils and solvents are often used as lubricants or additives to improve the processing characteristics of the materials, helping to prevent clogs and ensuring a smooth flow during production.

The presence of these elements is critical in achieving the desired physical properties of the final products, making this answer the most relevant to the practices typically seen in the plastics industry. Other factors mentioned in other options do not directly relate to the core processes involved in plastic manufacturing. For example, while metal shavings and dust might be relevant in industries that work with metals, they do not apply to plastics. Similarly, high BOD and ammonia are more pertinent to wastewater treatment discussions, rather than plastic production. Organic compounds are sometimes part of the discussion regarding raw materials, but they don't encapsulate the operational environment as effectively as high temperatures, oils, and solvents do in terms of the actual manufacturing process.