Please select all correct statements about the different table types.

Answer options:

A.An activity table can connect to the external data source
B.A virtual table needs a data provider and data source
C.You can convert an existing standard table to a virtual table
D.You can not change the ownership of the standard table after its creation

Correct Answers: B and D 
The Dataverse provides the three types of tables: Standard — this is a custom table type that users create the most. These tables store data and navigation for model-driven apps.
Activity — this is a special custom table type for storing activity information like appointments, phone calls, emails, tasks, etc.
Virtual — this custom table type has columns that bring data from external sources, like Azure SQL Database or Azure Cosmos DB.Option B is correct because a virtual table requires the data provider and data source. You need to create a custom data provider or use an OData Data provider. For the custom data provider, you develop and register the plug-in that, using the data source, brings data to the Dataverse virtual table.
Option D is correct because after you create a standard table with one of the ownership types: user (group) or organization, you cannot change it.
Option A is incorrect because an activity table does not have access to the external data. This table type provides the columns that help you properly store the data, such as start and end time, duration, due date. Also, the Dataverse provides columns to capture the activity purpose, like subject and description.
Option C is incorrect because you cannot change the table type after table creation.
For more information about the Dataverse table types, please visit the below URLs: 

https://docs.microsoft.com/en-us/powerapps/maker/data-platform/types-of-entities
https://docs.microsoft.com/en-us/powerapps/maker/data-platform/create-edit-virtual-entities