The statement that qualifies as a claim is: "Production of single-use plastics should be banned."
This is a claim because it presents a specific position that can be argued for or against and could be supported by evidence and reasoning. The other statements, while they express positions, are more factual or general. "Single-use plastics are unable to be recycled" is a factual statement (though the argument could be made for why this is problematic, it is not itself a claim), and "Single-use plastics can be harmful" suggests harm but does not take a definitive stance that advocates for a specific action or position.