17.     approximately how much of the world's population lives in cities?  
            a.  75 percent    b.  25 percent    c.  80 percent    d.  50 percent 

I think the answer is D im not 100 percent sure

5050%

Explanation: took the test

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.

your answer should be c) enjoy!