In the server room you find a box with five $15 \mathrm{~GB}$ hard disks. If you were to implement a RAID 5 solution using all five disks, how much storage space would you have for the actual data?
A. $75 \mathrm{~GB}$
B. $60 \mathrm{~GB}$
C. $30 \mathrm{~GB}$
D. $45 \mathrm{~GB}$