Final answer:
Juliet's reaction to Romeo knowing her thoughts is best described as embarrassed and wishing she hadn't shared her feelings.
Step-by-step explanation:
Juliet's reaction to Romeo knowing her thoughts is best described as a) embarrassed and wishing she hadn't shared her feelings. In the given text, it is mentioned that Juliet's heart stopped a beat before it pulsed on with leaps that she felt in her neck. This suggests that she feels shocked and embarrassed by the fact that Romeo overheard her innermost thoughts. Therefore, option a) is the most accurate choice.