Answer:
a. “pained furrows between her brows”
Step-by-step explanation:
This is the sentence that best conveys the idea that Kathryn is tense, and possibly unhappy. In this line, we learn that Kathryn is tensing her brow in an expression of displeasure ("furrows between her brows"). We also learn that this expression arises from something that bothers her significantly (pained). Therefore, we can guess what her mood is based on her facial expressions.