I believe that the English Bill of Rights influenced the American colonies by providing a model of representative government.
I don't think A is correct because at the time, those three branches of government didn't exist yet. C is also incorrect because Britain didn't want to give America any freedoms. D is incorrect because that has nothing to do with either Bill of Rights or the American governmental system.
Sources are used in a paper to show what ideas inspired you and whose theories you would be using and you cite the sources in order to avoid plagiarism. If you don't have sources, your paper will not be valid and you could get accused of plagiarism. The more sources you use the better but you should keep in mind that they need to be important for the paper and used with a purpose and not just to increase the number of sources.