1) Explanation

Let's break down the sentence to understand the context and the meaning required for the blank:
- "The protest at the capital yesterday was an absolute $\qquad$ ;"
- This opening clause establishes a strong, negative characterization of the protest. The word in the blank must describe something that was a complete failure or a disaster.
- "while the activists had the best of intentions, the demonstration showed a complete lack of organization and was actually counterproductive to their cause."
- This second clause provides the reason for the negative characterization. The key phrases are "complete lack of organization" and "actually counterproductive to their cause." This means the protest was a chaotic mess that not only failed but actively harmed its own objectives.

Now, let's analyze the given options:
- A. stalemate: A situation where neither side can make progress; a deadlock. While the protest was "counterproductive" (implying no positive progress), "stalemate" doesn't capture the element of disorganization or the disastrous, humiliating nature of the event itself. It implies a static, stuck situation, not necessarily a messy failure.
- B. debacle: A sudden and ignominious failure; a complete collapse or breakdown. This word perfectly describes a complete and often humiliating failure or breakdown. This aligns well with a "complete lack of organization" leading to a "counterproductive" outcome, painting the protest as a disaster.
- C. impasse: A situation where no progress is possible, typically due to a disagreement; a deadlock. Similar to "stalemate," it focuses on a standstill or an inability to proceed, rather than a chaotic, self-defeating, and utter failure of the event itself.
- D. fiasco: A thing that is a complete failure, especially a humiliating or ludicrous one. This is a strong synonym for "debacle" and precisely fits the description of a disorganized and counterproductive event that failed spectacularly and perhaps even embarrassingly.

- E. obstacle: A thing that blocks one's way or hinders progress. An "obstacle" is something that causes difficulty or blocks a path. The blank, however, describes the nature of the protest as a failure in itself, not something hindering it from the outside.
- F. enigma: A mysterious or puzzling person or thing. This is completely irrelevant to the context of a poorly executed and failing event. The problem isn't that the protest was mysterious, but that it was a clear failure.

Conclusion:

The blank requires words that signify a complete, disastrous failure, especially one marked by disorganization and self-defeating outcomes. Both "debacle" and "fiasco" convey this meaning perfectly.

The correct answers are B. debacle and D. fiasco.