The new operating system designed by MegaTech for the Belmont library will not only meet the needs of the library, but it also has the flexibility and power to manage larger institutional databases.

A. but it also has the flexibility and power to manage
B. but it also has the flexibility and power of managing
C. but also have the flexibility and power to manage
D. and also the flexibility and power of managing
E. and it also has such flexibility and power that it can manage

OA is C. this question came out of McGraw cd.
I’m confused b/c isn’t operating system singular so you need “has” vs “have”

I’m thinking that the “it” is ambiguous b/c it could refer to operating system or library. So you could eliminate a and b.

Any ideas, guys?