What is the most economical way to achieve this goal?

A customer has a single frame IBM TS4500 Tape Library with six 3592-E07 drives. A new open systems server was recently purchased and, because of budget constraints, the customer has decided to use less expensive LOT-7 tape media and drives while protecting investment in existing tape cartridges.

What is the most economical way to achieve this goal?
A . Add six LOT-7 drives in the existing frame.
B . Add six LOT-7 drives in a new frame.
C . Replace the frame and add LOT-7 drives.
D . Replace 3592 drives with LOT-7 drives in the existing frame.

Answer: B