This configuration will support two host failures by using RAID-6 (Erasure Coding), which creates two parity segments for each data segment. It will use the least amount of hosts among the options, because RAID-6 requires a minimum of six hosts for FTT=2. It will also minimize storage capacity usage, because RAID-6 uses less disk space than RAID-1 (Mirroring), which creates a full copy of each data segment12
A. 6 Hosts, FTT=2, RAID 1 is not a correct option, because it will not minimize storage capacity usage. RAID-1 will use more disk space than RAID-6, because it will create three copies of each data segment for FTT=212
C. 5 Hosts, FTT=2, RAID 5/6 is not a correct option, because it will not support two host failures. RAID-5 requires a minimum of four hosts for FTT=1, and RAID-6 requires a minimum of six hosts for FTT=2. With five hosts, neither RAID-5 nor RAID-6 can tolerate two host failures12
D. 5 Hosts, FTT=2, RAID 1 is not a correct option, because it will not support two host failures or minimize storage capacity usage. RAID-1 requires a minimum of five hosts for FTT=2, but it also requires an additional host as a witness to maintain quorum. Therefore, with five hosts, RAID-1 can only tolerate one host failure. Moreover, RAID-1 will use more disk space than RAID-6, because it will create three copies of each data segment for FTT=212
References: 1: Availability Attributes for vSAN VM Storage Policies - VMware Docs 2: Planning Capacity in vSAN - VMware Docs
