The SAP Data Flow Diagram (DFD) is an artifact from the SAP Reference Solution Architecture that shows which data objects are exchanged between SAP application components in a given end-to-end scenario. The DFD uses a graphical representation to show the flow of data between different components of a system.
The SAP Data Object Diagram (DOD) is also an artifact from the SAP Reference Solution Architecture, but it does not show the flow of data between different components. The DOD shows the structure of data objects, including their attributes and relationships.
The SAP Data Component Diagram (DCD) is an artifact from SAP Signavio Process Explorer, which is a tool for modeling business processes. The DCD shows the different components of a system, including their relationships.
Therefore, the correct answer is option B.
Here is a table that summarizes the different artifacts and their purposes:

According to the SAP Reference Architecture Content: An Overview - Part 2 , the SAP Data Flow Diagram is an artifact that shows the flow of data through the SAP solution, from the source to the destination. It also shows which data objects are exchanged between the different components and services of the SAP solution, such as master data, transactional data, analytical data, or configuration data. The SAP Data Flow Diagram can help you to understand and communicate how data is created, transformed, and consumed in a SAP solution, and to identify and optimize the data integration points and dependencies.
The other options (A and C) are not correct for the artifact from the SAP Reference Solution Architecture that shows which data objects are exchanged between SAP application components in a given end-to-end scenario, because they either do not exist or do not show the data flow. For example:
Option A is not correct because there is no such artifact as SAP Data Object Diagram in the SAP Reference Solution Architecture content. The SAP API Business Accelerator Hub (api.sap.com) is a platform that provides access to SAP APIs, events, and related resources, but it does not provide any diagrams that show the data objects exchanged between SAP application components.
Option C is not correct because the SAP Data Component Diagram is not an artifact that shows the data flow, but rather an artifact that shows the main components and services that constitute the target application architecture, as well as their relationships and interactions. The SAP Data Component Diagram does not show which data objects are exchanged between the different components and services of the SAP solution. The SAP Signavio Process Explorer is a tool that helps you to model, analyze, and optimize business processes, but it does not provide any diagrams that show the data flow.