Explanation:
Statement in this answer will show correct results because usage of operator LIKE and format mask ‘_A%’ extract the last names of those employees who have the letter “A” as the second character in their names. Symbol ‘_’ in format mask substitute exactly one symbol and cannot be NULL.
Incorrect Answers:
2: This statement will return only names starting from symbol ‘*’. It cannot be used as substitution symbol.
3: Usage of equity operator here is not appropriate in this case: query will look exact for first symbol ‘_’, it will not be considered as substitution symbol.
4: This statement will return only names starting from symbol ‘*’. It cannot be used as substitution symbol.
OCP Introduction to Oracle 9i: SQL Exam Guide, Jason Couchman, p. 61-67
Chapter 2: Limiting, Sorting, and Manipulating Return Data

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