If you kept your eye on the scale -
passage-discussion-t5719.html - this should have been a manageable question.
(A) is unsupported. We never hear about the English and colonials sharing (or not sharing) any thoughts about whether they shared a common political vocabulary. The passage only mentions what the colonials thought.
(B) is true, but too narrow to be the main idea.
(C) is correct - and is seen throughout the passage, particularly paragraphs 1 and 3.
(D) is true, but, like (B), is too narrow.
(E) is again too narrow. While this topic is discussed in the last paragraph, this is far from the main idea. It's an explanation for the main idea.
I hope that clears it up.