Answer:
Most often this is the one scene that sets the story off in the mind of the author. The scene will haunt him/her until he writes it down. Once the scene is in place, the writer can think about the various backstories that might have led the character to this particular scene.
Answer:
The controlling idea is the main concept.Supporting details support the idea.
Explanation:
The controlling idea and supporting details helps understand the point of the story/text.
