The hiring manager is aware that stress at work is unavoidable. Learning how you cope with individual challenges at work and the day-to-day stress of the position is important to determine if you have what it takes to succeed in this role. This answer can be pulled from any previous work experience, not just pharmacy. I would suggest bringing real-life examples into your answer. The key here is not to pretend stress doesn't exist, or that you aren't affected by it, but to specifically answer how you don't let stress affect your work performance with helpful coping mechanisms.