What is found in the stroma of a chloroplast?

The stroma of a chloroplast is a fluid-filled space that surrounds the thylakoid membranes and plays a crucial role in photosynthesis. It contains enzymes, DNA, ribosomes, and various metabolic intermediates that are essential for the synthesis of organic molecules. During the Calvin Cycle, which occurs in the stroma, carbon dioxide is converted into glucose using ATP and NADPH produced in the thylakoid membranes. This process emphasizes the stroma's function as the site where key biochemical reactions occur that contribute to the formation of carbohydrates from carbon dioxide and water.

While chlorophyll is indeed a vital pigment found in the thylakoid membranes and necessary for capturing light energy, it is not located in the stroma. Water and salts are present in chloroplasts, but they do not accurately describe the specific biochemical activities that occur in the stroma. Though carbon dioxide is required for photosynthesis, the presence of oxygen is more associated with the thylakoid reactions rather than the stroma itself, where synthesis of organic molecules mainly takes place. Thus, the correct answer highlights the stroma's role in the synthesis of organic molecules, distinguishing its function from the other components mentioned.