Which of the following statements about mitochondria is TRUE? A. The outer mitochondrial membrane is impermeable to ions and small molecules. B. Mitochondria are small round organelles that are often associated with actin filaments of the cytoskeleton. C. In sperm cells, mitochondria are seen wrapping tightly around the nucleus. D. Mitochondria are large enough to be seen with modern light microscopy, and can occupy as much as 20% of cytoplasmic volume.