A customer has a Dell EMC SC9000 with six SC420 enclosures. The enclosure configuration is as follow:

• Two enclosures have write-intensive SSD drives
• Four enclosures have read-intensive SSD drives

As a general guideline, what is recommended for spare drive assignment?

A. 1 spare per shelf

B. 1 spare per drive type

C. 2 spares per drive type

D. 3 spares per drive type