Answer:
1. D
2. D
3. B
4. D
5. B
Step-by-step explanation:
In 1. D the use of a comma and a coordinating conjunction emphasize de relationship between the two clauses.
In 2. D using a subordinating conjunction -so- the second clause depends on the first one
In 3. B the use of a period corrects run-on sentences and is possible because none of the sentences is too short thus avoiding choppy sentences
In 4.D using the coordinating conjunction and the two clauses are paired and their relationship is emphasized.
In 5. B the use of a comma before the coordinating conjunction but establishes a relationship of contrast between the two clauses (Even though car insurance is expensive, the state requires every driver to have it).