Explanation

Zonal Reserved Instances are the correct choice because:

• Zonal Reserved Instances provide capacity reservation in a specific Availability Zone within an AWS Region
• They guarantee capacity for EC2 instances in that particular Availability Zone
• This is ideal when you need to ensure compute resources are available in a specific zone for compliance, performance, or architectural requirements

Why not the other options:

• EC2 Instance Savings Plans and Compute Savings Plans: These provide cost savings but do not guarantee capacity reservation in specific Availability Zones
• Regional Reserved Instances: These provide flexibility across Availability Zones within a region but do not guarantee capacity in any specific zone

When you need to reserve capacity in a specific Availability Zone, Zonal Reserved Instances are the appropriate AWS purchasing option.