Answer:
b. Although the dentist did not find anything wrong, Sue's mouth still hurt.
Step-by-step explanation:
a. The dentist did not find anything wrong with Sue's teeth.
- simple: clause can’t stand on its own as a sentence.
b. Although the dentist did not find anything wrong, Sue's mouth still hurt.
- complex: by linking an independent clause with a dependent clause
c. The dentist did not find anything wrong with her teeth, but Sue continues to have a toothache.
- compound: There are two independent clauses, but when they are put together with the word "but" as in this case, the result is a compound sentence.
d. Although the dentist found nothing wrong with Sue's teeth, she still had a toothache, so she went to bed.
- Compound complex: sentence having at least one dependent clause and two or more independent clauses