The correct answer is a) mitochondria.
The citric acid cycle, also known as the Krebs cycle, is a crucial metabolic pathway that occurs in the mitochondria of plant cells. This cycle plays a significant role in cellular respiration, helping to convert carbohydrates, fats, and proteins into carbon dioxide, water, and energy in the form of ATP.
While chloroplasts are responsible for photosynthesis in plants, where light energy is harnessed to produce glucose, the mitochondria are where the energy stored in that glucose is utilized through processes like the citric acid cycle. Ribosomes are involved in protein synthesis, and the nucleus contains the cell’s genetic material, thus none of these options are correct places for the citric acid cycle.