To determine the number of columns presented after executing the given query, let's break down the query and analyze it step by step:
The query is:
SELECT address1||','||address2||','||address2 "Adress" FROM employee;
Here, we are selecting three columns: address1, address2, and address2 (renamed as "Address" using the alias "Adress").
Each column is concatenated with a comma (',').
So, the query will produce three columns: address1, address2, and Address.
Therefore, the correct answer is C) 3.