Final answer:
Liz is observing chloroplasts under the microscope, which are green organelles where photosynthesis occurs, characterized by the presence of chlorophyll.
Therefore, the option B is correct.
Step-by-step explanation:
Liz is looking at chloroplasts, which are the organelles where photosynthesis takes place in plant and algal cells. Chloroplasts are characterized by their green color, which is due to the presence of chlorophyll, a pigment that captures the energy of sunlight. Chloroplasts have a complex inner membrane system that includes the thylakoid membranes, where the light reactions of photosynthesis occur. These membranes are arranged in stacks called grana, which are surrounded by stroma, a fluid-filled space. The unique structure of the chloroplasts, such as the double membrane and the highly dynamic thylakoid system, enables them to efficiently carry out photosynthesis, which is fundamental to the energy flow within most ecosystems.