The correct answer is B. The files are used in a mission-critical analytics pipeline that is continually accessed, which means they need to be readily available with low latency. Standard storage class is appropriate for frequently accessed data. Although dual-regional storage would provide higher availability, it is more costly and not necessary in this case because the users are all in a single region (Boston, MA). Therefore, configuring regional storage with a Standard storage class is the optimal balance between cost and performance for this scenario.