Disposable plastic plates should not be used because they are made of (d) non-biodegradable materials.
Explanation: Non-biodegradable materials like most plastics cannot be broken down by natural organisms, leading to them accumulating in landfills and polluting the environment.
Why the other options are incorrect:
(a) They are made of materials with light weight:
While the lightweight nature of plastic contributes to its convenience, it is not the primary reason why disposable plastic plates are harmful to the environment.
(b) They are made of toxic materials:
Some plastics can contain toxic chemicals, but this is not always the main reason why disposable plastic plates are considered environmentally problematic.
(c) They are made of biodegradable materials:
Biodegradable materials can decompose naturally, so they are not considered environmentally harmful. However, most disposable plastic plates are made from non-biodegradable plastics.