Final answer:
The word 'subtle' in the given context means sounds that are faint or not easily noticeable. Hence, the answer to the student's question is option B, faint or bold.
Step-by-step explanation:
In the phrase "Janie heard subtle rhythms of Bahaman drummers," the word subtle refers to sounds that are faint or not easily noticeable rather than being loud and distinct. The correct answer to the definition of subtle in this context is option B, faint or bold. Here, 'bold' is the antonym included to define the subtleness by contrast, indicating the rhythms were delicately perceived rather than being conspicuous or assertive.