(a): This appears to show a pattern of blue dots, possibly representing chloroplasts or similar organelles, not mitochondria.
(b): This shows a detailed depiction of a mitochondrion with its characteristic double membrane and inner folds called cristae, which increase the surface area for energy production.
(c): This image looks like a brick wall, possibly symbolizing a rigid structure like a cell wall, which is unrelated to mitochondria.
(d): This resembles a chemical or molecular structure, unrelated to the detailed physical structure of a mitochondrion.