Answer:
X
Explanation:
Assume your diagram is like the one below.
X represents a mitochondrion.
That's where the Tricarboxylic Acid Cycle converts a single glucose molecule into six molecules of CO₂.
W is wrong. It represents a vacuole, which can store both nutrients and waste products for later elimination.
Y is wrong. It represents the nucleolus, which plays a critical role in the synthesis of ribosomes.
Z is wrong. It represents the cytoplasm, which is where cell processes like glycolysis and protein synthesis take place.