Answer:
Ocean and river pollution: it has been solved but the problem is that the machine that filters plastic from the water is making it difficult for Fishermen to catch fishes.
that's the only I can think of that could cause problem
Out of the following choices, fossil fuels is the largest reservoir of carbon in the world. A couple of other reservoirs of carbon are dissolved in the ocean and in plants.
The endoplasmic reticulum, or ER, and Golgi apparatus, prepare molecules, including proteins, hormones and lipids, and package them in vesicles for transport. Rough ER is studded with ribosomes that synthesize proteins, while the smooth ER manufactures lipids.