Which option is the default pricing model for Amazon EC2 instances?

On-Demand Instances are the default pricing model for Amazon EC2 instances. They allow users to pay for compute capacity by the second, with no long-term commitments or upfront payments. They are suitable for applications with short-term, irregular, or unpredictable workloads that cannot beinterrupted3. Savings Plans are a pricing model that offer significant savings on Amazon EC2 and AWS Fargate usage, in exchange for a commitment to a consistent amount of usage (measured in $/hour) for a 1-year or 3-year term. Spot Instances are a pricing model that offer spare Amazon EC2 compute capacity at up to 90% discount compared to On-Demand prices, but they can be interrupted by AWS with a two-minute notice when the demand exceeds the supply. Reserved Instances are a pricing model that offer up to 75% discount compared to On-Demand prices, in exchange for a commitment to use a specific instance type and size in a specific region for a 1-year or 3-year term.