Reports must be _____, _____, _____ and _____.

The correct formulation for reports in a law enforcement context emphasizes the need for them to be clear, concise, accurate, and complete.

Clarity is vital in ensuring that the report is easily understood by anyone who reads it, preventing misinterpretations that could arise from vague language. Being concise helps to maintain the reader's engagement and ensures that only the relevant facts are included, focusing on the key points without unnecessary elaboration.

Accuracy is crucial as it reflects the factual correctness of the information provided, ensuring that it can be relied upon in legal proceedings or investigations. Lastly, completeness ensures that all necessary details are included, painting a full picture of the incident or situation addressed in the report. This combination of qualities strengthens the report's utility and its effectiveness in meeting legal and procedural standards.

The other choices contain attributes that do not align with effective reporting standards in law enforcement. For instance, being subjective or opinionated detracts from the objectivity required in official reports, while being vague or ambiguous can lead to misunderstandings and a lack of clarity. Thus, the attributes of clear, concise, accurate, and complete are essential for producing effective reports in law enforcement.