The correct answer is C because the NDB Database Agent service is responsible for scheduling and monitoring the NDB-related operations, such as provisioning, patching, cloning, and restoring databases. The NDB Database Agent service is deployed on the NDB server and on each of the database server VMs provisioned by NDB. It contains the tools required to perform each task and communicates with the NDB server through the NDB API. The other options are not correct because they describe different components or functions of the NDB solution. Option A is not correct because the transaction logs are not stored by the NDB Database Agent service, but by the NDB Time Machine service, which is a distributed file system that stores the database snapshots and logs. Option B is not correct because the source databases are not hosted by the NDB Database Agent service, but by the database server VMs, which are virtual machines that contain an instance of the database engine software and the database files. Option D is not correct because the NDB Database Agent service does not contain an instance of the database engine software, but only the tools required to perform the NDB-related operations. The database engine software is installed on the database server VMs, which are provisioned by NDB using the profiles defined by the administrator. References: Nutanix Database Management & Automation (NDMA) course, Nutanix Certified Professional - Database Automation (NCP-DB) certification, Nutanix NCP-DB Certification Exam Syllabus and Study Guide, Nutanix Support & Insights