Final answer:
The cell connections most likely present between the cells forming the blood-brain barrier are C) Tight junctions, providing a selective membrane that prevents substances from leaking between the cells.
Step-by-step explanation:
The cell connections most likely present between the cells forming the blood-brain barrier are C) Tight junctions. These tight junctions create a highly selective membrane that is crucial for maintaining the central nervous system's protected environment. The blood-brain barrier is characterized by epithelial cells that are held tightly against each other by proteins, preventing materials from leaking between the cells. Unlike gap junctions that form intercellular passageways or desmosomes and adherens junctions that provide mechanical stability but allow materials to pass, tight junctions block the movement of substances through the extracellular space between the cells, making them the essential junctions for the blood-brain barrier.