The correct answer is A.
Taking long daytime naps would not be helpful to reduce Heather's stress because their would alter her sleep cycle, causing her to sleep less at night and thus, be more tired during the day. Also, long daytime naps tend to make people fell more tired and sleepy, rather than refreashed and clear-minded.
On the other hand, a short, twenty-minute nap, could help her if she was feeling too overwhealmed by her obligations.