Which statement is not correct?

a. It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because having multiple physical drives allows for parallel retrieval, which results in much more improved performance.

b. It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because reliability can be improved by introducing some measure of data redundancy.

c. With bit-level data striping, every disk participates in each read or write operation.

d. Using error-correcting codes for fault tolerance requires extra storage space, almost as much as when opting for disk mirroring.