निम्नलिखित में से कौन सा बहुलक (polymer) प्राकृतिक पर्यावरणीय परिस्थितियों में जैव-निम्नीकरणीय (biodegradable) है?

Identify the correct statements regarding fibers, plastics, and detergents in daily life: (J) Synthetic fibers such as nylon and polyester are more durable than natural fibers. (K) Thermoplastics can be softened and reshaped repeatedly upon heating. (L) Detergents form insoluble precipitate/scum with calcium and magnesium ions in hard water. (M) Non-biodegradable plastics pose a severe threat to the environment.