Final answer:
The correct sentence is option B: Washington lost nearly all his teeth, so a French dentist made him a set from carved rhinoceros ivory.
Step-by-step explanation:
The correct sentence is option B: Washington lost nearly all his teeth, so a French dentist made him a set from carved rhinoceros ivory. The word 'so' indicates the cause-and-effect relationship between Washington losing his teeth and the French dentist making him a set of teeth. This makes the sentence grammatically correct and clarifies the sequence of events.