Since prokaryotic cells lack membrane-bound orgnelles, many metabolic functions in the cell take place ...

a - within the ribosomes.

b - at the DNA.

c - in the cytoplasm.

d - at the cell wall.

C - In the cytoplasm

Explanation:

The cytoplasm of prokaryotic cells hold all the molecules of the cells, molecules that are required for metabolism - big and small.

The lack of compartmentalization is what make it seem as though there are no organelles but in actual fact, the molecules that make up those organelles can be found in prokaryotic cytoplasm.