Which of the Following Demonstrates the Correct Order of the Phases

Which of the following demonstrates the correct order of the phases involved in a lightning stroke?

A) Step leaders,return stroke,separation of charges,flow of negative charge into ground,dart leader
B) Charge separation,step leaders,return stroke,flow of negative charge into ground,dart leader
C) Dart leader,charge separation,flow of negative charge into ground,step leaders,return stroke
D) Charge separation,dart leader,step leaders,flow of negative charge into ground,return stroke