These packaging's must be well constructed with closures made of good quality polyethylene or other suitable plastic that are sufficiently tight to prevent leaking and sifting.

• A. Metal
• B. Plastic
• C. Glass
• D. Wood

Answer: (B)

Preventing leakage and sifting hinges on the closure being able to form a tight, reliable seal with the container. Plastic closures, especially those made from polyethylene or similar plastics, are ideal because they can be molded to precise threads and tolerances and can incorporate liners to enhance the seal. They are light, cost-effective, and resistant to many chemicals, while also not rusting or breaking easily. Metal closures can be prone to corrosion or reactions with contents and may not seal as consistently for powders; glass closures are strong but heavy and brittle; wood is porous and can absorb moisture and particles, compromising the seal. So using polyethylene or another suitable plastic for closures provides the right balance of tight sealing, durability, and practicality for preventing leakage and sifting.