Your company's test suite is a custom C++ application that runs tests throughout each day on Linux virtual machines. The full test suite takes several hours to complete, running on a limited number of on-premises servers reserved for testing. Your company wants to move the testing infrastructure to the cloud, to reduce the amount of time it takes to fully test a change to the system, while changing the tests as little as possible. Which cloud infrastructure should you recommend?

Google Compute Engine managed instance groups with auto-scaling is the best choice because it allows the company to provision and deprovision Linux VMs dynamically based on demand. This enables parallel execution of tests across many machines, significantly reducing the total test suite execution time. Auto-scaling ensures resources are only consumed when needed, optimizing costs. Unmanaged instance groups would require manual scaling, defeating the purpose of reducing test time efficiently. Google Cloud Dataproc is designed for big data processing, not for running custom C++ test suites. Google App Engine is a Platform as a Service (PaaS) for deploying web applications, not suitable for running arbitrary C++ executables on Linux VMs.