Final answer:
The correct plural negative command to complete the sentence is 'No coman' in Spanish.
Step-by-step explanation:
The correct plural negative command to complete the sentence '______ galletas' is 'No coman'. The verb 'comer' means 'to eat' in Spanish, and when negating a plural command, you use the form 'no + verb in infinitive form'. For example, 'No coman las galletas' means 'Don't eat the cookies'. So in the given sentence, we use 'no coman' to indicate 'Don't eat cookies'.
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