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