Why is glucose not a polymer ?

Because it is a simple sugar. It's called a monosacharide. A polysacharide (polymer, but better for this situation) would be something like starch. The difference between the two is that glucose is a single group of elements, or a molecule (C6H12O6 is the chemical compound) and a polymer would contain tons and tons of these sugar molecules. 

Ithink the answer is b
not sure