> 1. There are 50 stars on America's national flag, each ______ a state.
> A. standing for
> B stands for
> C represented
> D to represent
> In my opinion the answer of the question should be B
A is correct. Too many people (especially Chinese learning English) write two sentences separated by a comma. In English grammar, that's incorrect. If needed, the comma can be changed to semicolon so the second sentence further explains the first one.