An Operating System $($OS$)$ has already been installed on a Hyper$-$V Virtual Machine hard disk. In the BIOS settings of the VM$,$ which one of the following should be first on the Startup$/$Boot order list so that the VM will not attempt to boot from a CD$?$

a$.$

Virtual switch

b$.$

Floppy

c$.$

Legacy network adapter

d$.$

IDE