The answer to this question is C. Partially Correct Assumption.
Explanation:
The cloud provider will take care of the physical security of the infrastructure, such as the data centers and the network. However, the responsibility for application security still lies with the organization that owns the application. This includes things like ensuring that the application is coded securely, that it is properly configured, and that it is regularly updated with security patches.
Therefore, the assumption that security will entirely be the service provider's responsibility is partially correct. The service provider will take care of some aspects of security, but the organization still has a responsibility to ensure the security of their application.
Here is a table that summarizes the different aspects of security that are the responsibility of the cloud provider and the organization: