What is the maximum size of an IOS file that could be loaded if the original IOS is also kept in flash?

Refer to the exhibit.

The technician wants to upload a new IOS in the router while keeping the existing IOS.
What is the maximum size of an IOS file that could be loaded if the original IOS is also kept in flash?

A.
3MB

B.
5MB

C.
7MB

D.
4MB