What is the least expensive solution that is best suited to solve the database performance problem?

A customer is experiencing insufficient performance of its 15 TB production database. The bottleneck has been identified as disk I/O performance. The database volumes are distributed optimally across 300 GB/15k rpm SAS disks on its existing IBM Storwize V7000.

What is the least expensive solution that is best suited to solve the database performance problem?
A . Add an IBM Storwize V5010 and move the database
B . Add NL-SAS drives to the IBM Storwize V7000 with Easy Tier
C . Add SSDs to the IBM Storwize V7000 and manage them with Easy Tier
D . Add an IBM FlashSystem and virtualize behind the IBM Storwize V7000

Answer: B