Answer:
Z
Step-by-step explanation:
The first stage of cellular respiration is called GLYCOLYSIS, where glucose is broken down into pyruvate. Because glycolysis occurs irrespective of whether there is oxygen or not, it occurs in all organisms. Hence, glycolysis occurs in the CYTOPLASM of their cell.
In this question, a diagram was given as an attachment. In the diagram, letters W, X, Y amd Z are used to represent organelles in the cell. Letter Z represents the cytoplasm, hence, the first stage of cellular respiration takes place in Z.