Which layer does VMware vSAN provide redundancy for Virtual Machine (VM) files?

At which layer does VMware vSAN provide redundancy for Virtual Machine (VM) files?
A. At host storage controller (RAID) only.
B. In VMware vSAN only.
C. In VMware vSAN and virtual machine (VM) storage policies.
D. At host storage controller (RAID) and VMware vSAN.