Final answer:
The best technique to visualize the movement of unlabeled vesicles along microtubules is live cell fluorescence microscopy.
Step-by-step explanation:
The best technique to visualize the movement of unlabeled vesicles along microtubules would be live cell fluorescence microscopy (option B). This technique allows for the observation of dynamic processes in living cells. Unlabeled vesicles can be visualized using this method by tagging them with a fluorescent marker.
Immunofluorescence microscopy of fixed material (option A) would not be suitable for visualizing unlabeled vesicles because it requires the use of antibodies.
Computer-enhanced digital video microscopy (option C) can also be used to visualize movement, but it may not provide the same level of detail as live cell fluorescence microscopy.