AWS Cost Explorer and AWS Compute Optimizer are the correct services for identifying rightsizing opportunities for Amazon EC2 instances.

AWS Cost Explorer helps analyze AWS costs and usage patterns, and it provides rightsizing recommendations based on historical usage data.

AWS Compute Optimizer specifically analyzes resource utilization metrics of EC2 instances and provides recommendations for rightsizing to optimize performance and reduce costs.

The other options are not designed for EC2 rightsizing:

• AWS Billing Conductor is for customizing billing data and creating billing views
• Amazon CodeGuru is for code quality and performance analysis
• Amazon SageMaker is for machine learning model development and deployment