What operation does the search look after?

Answer options:

A.Searches in columns listed.
B.Searches across all tables and not column specific.
C.Searches only data in the last day
D.Searches data only in the last month

Correct Answer: B Option B is correct. The search will search across all columns in tables specified.
Option A, C and D are incorrect. The search operator will respect the query time bound parameter and it will search across all columns in a table.
Reference: 

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