The correct answer is C, the 3-year, All Upfront, Standard Reserved Instance (RI). This option provides the highest average cost savings compared to an On-Demand Instance because it requires a full upfront payment and commits to a longer term of 3 years. AWS offers more significant discounts for longer terms and larger upfront payments. This is ideal for predictable workloads that can be planned and managed for an extended period, allowing customers to benefit from the maximum savings.