Contents of the CUSTOMERS table

Note: The ST column name is truncated,this represents the STATE column.
-Which of the following is a valid SQL statement based upon the contents of the CUSTOMERS table?
A) SELECT INITCAP(firstname,lastname)FROM customers;
B) SELECT LENGTH (city,state,zip)FROM customers;
C) SELECT customer#,NVL2(referred,'Referred','Not Referred')FROM customers;
D) SELECT INITCAP((firstname), ( lastname))FROM customers;

Question

Contents of the CUSTOMERS table
  ​
Note: The ST column name is truncated,this represents the STATE column.
-Which of the following is a valid SQL statement based upon the contents of the CUSTOMERS table?
A) ​SELECT INITCAP(firstname,lastname)FROM customers; 
B) ​SELECT LENGTH (city,state,zip)FROM customers; 
C) ​SELECT customer#,NVL2(referred,'Referred','Not Referred')FROM customers; 
D) ​SELECT INITCAP((firstname), ( lastname))FROM customers;

Quizplus · Accepted Answer

Option A and D are invalid because there are no columns named "firstname" and "lastname" in the table. Option B is also invalid as the function LENGTH() only accepts one argument.
Option C is valid as it selects the customer number along with the value "Referred" or "Not Referred" based on the presence of data in the "referred" column (using the NVL2 function).

Contents of the CUSTOMERS Table