Explanation:
Column name must be start with an alphabet.But not the reserved word of the oracle Incorrect answers
1: Number is the reserved word in oracle.So it is not the name of column.
2: Column name Not start with a numeric value so 1966_invoices is not a valid name.
4: Not start with a special character so #Invoices is not valid.
5: option C is a valid so this option is not true.reference:
Reference:
Introduction to Oracle 9i: SQL - Creating and Managing Tables

---