The only example among these that is a water-conservation technique that also reduces water pollution is c) factories reusing cooling water instead of returning it to a river.
A. 2
trust me i used to so this in middle school
So back in 1665 Robert hook was able to view cells and describe them along with pictures, the reason he was able to see cells was because the microscope was invented a bit before, which allowed him to think about things differently, he was looking at a cork and saw squared objects, these objects were cells, according to him.
So while the cork was the reason he discovers cells on it in the first place,
The microscope was what allowed him to do that
So it’s (HOOKE LOOKING AT A CORK)
And it’s (THE INVENTION OF THE MICROSCOPE)
I’m assuming you mean 5g of magnesium :)