Regardless of whether a database or table name is case sensitive on the system, it must be referred to using the same lettercase throughout a given query.

Answer: Option A

This question is asking if you can use different letter cases when referring to a database or table name within a single MySQL query. For example, can you write "SELECT * FROM myTable" and "SELECT * from MyTable" in the same query?
The answer is True. MySQL does not care about the letter case when referring to database or table names. You can use any combination of uppercase and lowercase letters, but it's best to be consistent within the same query to avoid confusion.
So the answer is Option A: True.