Step 1: Understanding the planning sequence.
- (A): The initial phase of planning involves formulating assumptions about future conditions, as all plans rely on anticipated circumstances.
- (B): Following assumption formulation, the subsequent step is selecting the optimal alternative to guarantee the plan's practicality and feasibility.
- (C): A critical part of evaluating alternatives involves assessing the advantages and disadvantages of each.
- (D): The final stage is plan monitoring, which ensures that goals are achieved and allows for necessary modifications.
Step 2: Conclusion.
The correct sequence is:
(A), (B), (C), (D).
Final Answer:
\[
\boxed{\text{The correct answer is (1) (A), (B), (C), (D).}}
\]