Modern SCUBA equipment contains a rebreather. This allows you to breathe the same air many times and produces no bubbles.

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.

micro/nanoscale topography surface exhibits many prominent properties and is extensively employed in biomedical device, microfluidic device and energy device fabrication. additionally, the clinical applications of biomaterials can be largely expanded with of nanostructured surfaces.

the answer is c a tornado

d. planting trees

the trees take in carbon to make oxygen.