I am not sure you are setting up a SQL on VM or Physical. If it is VM, storage decision may vary as it is depends on the VM Host.
I recommend not to install SQL on C drive, dedicate the SQL for OS and OS only. So, it can be small but make sure to mirror the C drive, because if C drive give up whole sever needs to rebuilt.
As everyone suggest, RAID 10 much better than RAID 5 when it comes to IO. At the same time, RAID 5 works great on Indexing because it reads faster than RAID 10. RAID 10 good for LOG and TEMP DB. Many cases DATA and INDEX as well. We use RAID 10 most of the time.