A compartment is a logical container that can hold resources such as databases, compute instances, networks, etc. A compartment can be organized in a hierarchical fashion, with parent and child compartments1. After creating a compartment, you do not need to write any policies for it, unless you want to grant access to other users or groups2. Compartments are tenancy-wide, meaning that they are available across all the regions that the tenancy subscribes to3. A compartment allows you to isolate resources for different purposes, such as development, testing, production, etc. Therefore, statement C is false, and statements A, B, and D are true.
References: 1: Become an Oracle Base Database Services Professional (2023), Section 2.1.1:
Compartments 2: Base Database Service, Section 1.2.1: Compartments 3: Oracle Base Database Services 2023 Professional, Section 2.1.1: Compartments : [Oracle Cloud Infrastructure Documentation], Compartments and Subcompartments