Final answer:
Adjacent plant cells communicate via plasmodesmata, which are channels that allow small signaling molecules to move between cells for rapid coordination.
Step-by-step explanation:
Adjacent plant cells utilize plasmodesmata to rapidly communicate with each other. Therefore, the correct answer is a) Plasmodesmata.
Plasmodesmata are connections between the plasma membranes of neighboring plant cells. These channels allow small signaling molecules to diffuse between two cells, facilitating direct signaling. This type of cell communication is crucial for the coordination of activities within the plant. Signals are able to move across cells quickly and efficiently, making the entire plant a giant communication network. On the other hand, it should be noted that gap junctions serve a similar purpose in animal cells, allowing for the transport of ions, nutrients, and other substances.