Final answer:
The most suitable option to encourage the use of would be an Electric toothbrush.
Step-by-step explanation:
In this scenario, where the student has good bilateral upper extremity strength but decreased dexterity during toothbrushing, the most suitable option to encourage the use of would be an Electric toothbrush.
An electric toothbrush can help compensate for decreased dexterity as it has automated motion and requires less manual effort compared to other options. This can make toothbrushing easier and more effective for the student.
Additionally, an electric toothbrush often has special features like timers and different brush head options for specific needs, making it a versatile choice.