Choosing a 'NAS-rated HDD with quadruple the capacity of the current drive' is the right answer because NAS (Network Attached Storage) drives are optimized for use in servers where data reliability and continuous operation are crucial. They provide large storage capacity at a cost-effective price, compared to solid state drives. An 'External drive with equivalent capacity to the current drive' would not provide a significant space increase. The 'Thumb drive with minimal capacity' would be inappropriate, both in terms of reliability and capacity for server use. 'Dual capacity solid state drive' would offer less additional space than the NAS-rated HDD and would cost more for the amount of storage provided.