Concept:The idiom "Back to the drawing board" refers to restarting a process or plan from the initial stage after a failure.
Explanation:The phrase is used when a previous attempt or strategy has not worked, forcing one to go back and rethink the entire approach.
It strongly implies the need for a fresh start after a setback, not just minor adjustments.
For example, if a product prototype fails testing, the team must "go back to the drawing board" to redesign it.
This meaning matches exactly with "to start planning again because the previous plan has failed."
Option A ("to draw comparisons") is about pointing out similarities or differences, which is unrelated to restarting.
Option B ("to be a member of a planning group") merely describes a role, not the act of starting over after failure.
Option D ("to be fast at understanding a situation") focuses on quick comprehension, completely different from the idiom's core idea.
Thus, only Option C captures the essence of revisiting the original plan after it fails.
Answer:Option C: to start planning again because the previous plan has failed.