An Effective Transition Between Main Points

An effective transition between main points:

A) creates a clear,delineating division keeping two main ideas separate.
B) is a gateway to help listeners understand when a speaker is moving on.
C) is indicative of the care a speaker puts into developing a formal presentation.
D) should be identified as a transition so that listeners will notice it's there.
E) is a type of subtitle announcing the end of one idea and the start of the next.