Step 1: Understanding the sequence of planning.
- (A): The first step in planning is making assumptions about the future, as any plan must be based on anticipated conditions.
- (B): After assumptions, selecting the best alternative is the next step to ensure the plan is viable and realistic.
- (C): Weighing the pros and cons of each alternative is crucial to evaluating their feasibility.
- (D): Finally, monitoring the plan ensures that the objectives are met and adjustments are made as necessary.
Step 2: Conclusion.
The correct sequence is:
(A), (B), (C), (D).
Final Answer:
\[
\boxed{\text{The correct answer is (1) (A), (B), (C), (D).}}
\]