They are available at a significantly reduced cost is the correct option.

Spot virtual machines are offered at steep discounts because they run on spare capacity that the provider can reclaim when needed. This lower price point is the primary benefit when you accept the trade off of potential eviction, so Spot VMs make sense for interruptible, fault tolerant, or batch workloads where cost savings outweigh the risk.

They are specialized virtual machines optimized for GPU workloads is incorrect because Spot VMs are a pricing and eviction model and are not a specific hardware specialization. GPU optimized machines are selected by choosing GPU VM sizes instead.

They are intended for long running production services that must never be interrupted is incorrect because Spot VMs can be evicted with little notice and are not suitable for services that require uninterrupted availability.

They deliver burstable CPU performance for workloads with sporadic high CPU demand is incorrect because burstable CPU behavior is provided by specific burstable VM series and is unrelated to the Spot pricing and eviction model.

Full AWS Practitioner Certification Question