My best guess would be letter choice B: frequent. Choices C & D aren't synonyms of 'common' so they're automatically ruled out. Letter choice A is a synonym of 'common' however it doesn't fit the passage in my opinion. Therefore I would go with B: frequent.
Sentence 1: Opinion Sentence 2: Fact Sentence 3: Fact Sentence 4: Fact Sentence 5: Fact Sentence 6: Fact Remember, a fact is a statement that can be proved to be true and opinions are what people think.
