Answer:
a. The cells are connected by gap junctions.
Explanation:
Gap junctions are the points of connection between the adjacent cells of animal tissues. These structures are formed by proteins which in turn form narrow channels in the plasma membranes of the neighboring cells. These channels allow the small molecules to pass from the cytoplasm of the one cell to that of another. The spread of dye to the neighboring animal cells would have occurred by gap junctions present between these cells.