You are a SOC Analyst working at a company that is deploying Azure Sentinel. You are in charge for performing log data analysis to search for malicious activity, display visualizations, and perform threat hunting. 
To query log data, you use the Kusto Query Language (KQL). Often a result set from a KQL statement needs to be combined or joined with another result set. You need to understand how the order of a KQL statement impacts your expected results. 
When you perform union on two tables, the two tables require identical columns?

Answer options:

A.Only if the project operator is used.
B.Yes.
C.No.
D.Can’t say

Correct Answer: C Option C is correct. The results contain all columns from both tables.
Option B & A are incorrect. The result set will contain columns from both tables, even if the columns don`t match.
Reference: 

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