In GRUB’S configuration file you find the line root (hd1,4)
What is corresponding device name on a Linux system?

A.
/dev/hda4

B.
/dev/hda5

C.
/dev/hdb4

D.
/dev/hdb5

Explanation:
Hd0 Primary Master hda
Hd1 primary Slave hdb
hd2 secondary Master hdc
hd3 Secondary Slave hdd
Similarly partition number starts from 0 like array index in programming.