You have created an external table named ExtTable in Azure Data Explorer. Now, a database user needs to run a KQL (Kusto Query Language) query on this external table. Which of the following function should he use to refer to this table?

Answer options:

A.external_table()
B.access_table()
C.refer_table()
D.Only the table administrator can query the table.

Correct Answer: A 
After an external table is defined, the function external_table() should be used to refer to this table. Any database reader or user can query an external table.
Option A is correct. external_table() should be used to refer to the external table.
Option B is incorrect. Access_table() is not the valid function.
Option C is incorrect. There is no function like refer_table().
Option D is incorrect. Any database reader or user can query an external table.
Reference: 
To know more about how to query data in Azure Data Lake using Azure Data Explorer, please visit the below-given link: 

https://docs.microsoft.com/en-us/azure/data-explorer/data-lake-query-data