A. Ambiguous: If the coach's approval were ambiguous, it would be unclear whether the teammates could proceed with abandoning the game plan. This doesn't align with the context of the teammates deciding to have some fun.

B. Tacit: This fits the context well. Tacit approval means the coach's approval is understood or implied without being explicitly stated, allowing the teammates to make their decision.

C. Cautious: This doesn't seem fitting for the context. If the coach's approval were cautious, it would likely not lead the teammates to abandon the game plan.

D. Implicit: This aligns with the context. Implicit approval means it's understood without being directly expressed, giving the teammates the freedom to have some fun.

E. Enthusiastic: This doesn't seem appropriate. Enthusiastic approval would suggest the coach actively supports the decision, which may not be the case based on the teammates' choice to abandon the game plan.

F. Salubrious: This term means health-giving or healthy. It doesn't fit the context of the coach's approval for abandoning the game plan.

Based on the analysis, options B (tacit) and D (implicit) appear to be suitable choices in the context provided.

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