Final answer:
Cell membranes are best described as semi-permeable, allowing certain substances to pass while blocking others, thus maintaining homeostasis by controlling the internal environment of the cell. The correct option is C semi permeable
Step-by-step explanation:
The characteristic that best describes membranes is that they are semi-permeable. This means that cell membranes allow certain substances to pass through while blocking others. Membranes are not a tripled layer nor are they totally impermeable; instead, they have a structure that permits selective permeability. Structures such as phospholipid bilayers, proteins, and other molecules contribute to this selective permeability, allowing the cell to maintain homeostasis by carefully controlling the internal environment.
For example, membranes allow the passage of water and small non-polar molecules but restrict ions and polar molecules that are not lipid-soluble. This selective permeability is crucial for various cell functions, including growth, homeostasis, and passive transport, as it provides control over substances that enter and leave the cell. The correct option is C semi permeable