A server is equipped with 2 CPUs and 12x 8 GB DIMMs, for a total of 96 GB. The OS is not seeing all

A server is equipped with 2 CPUs and 12x 8 GB DIMMs, for a total of 96 GB. The OS is not seeing all the memory. Which memory mode should be configured so that all memory is seen by the OS?

A. Mirroring
B. Advanced ECC

C. Optimizer

D. Sparing

Reference https://www.dell.com/support/article/pk/en/pkbsd1/sln155709/memory-modes-in-dual-processor-11th-generation-poweredge-servers?lang=en#Sparing