In the Infrastructure as a Service (IaaS) model under the shared responsibility model, the cloud provider (e.g., Google Cloud) is responsible for the physical security of the infrastructure, including data centers, hardware, and the physical environment. The customer is responsible for managing the operating system, applications, and data.
Option B: Physical security is correct because it describes the cloud provider's responsibility in securing the physical aspects of the infrastructure.
References:
Google Cloud Shared Responsibility Model: Customer and Provider Responsibilities Google Cloud Security Overview: Physical Security Measures