The answer is d. This sentence helps you separate the actual warning and the word "warning" by using a colon. The other sentences don't make sense because they don't have that.
The answer is (d) because the rest of the sentence is the warning. And the colon goes in between ths the word warning and The.
The correct answer is D: "Warning: This cabinet contains dangerous electrical equipment." This option uses a colon correctly to introduce the warning. The other options contain punctuation errors or are structurally incorrect.
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