To solve this question, the user needs to be aware of the syntax used to specify runtime variables in SQL SELECT statements.

The correct answer is:

C. Ampersand

Explanation: In SQL SELECT statements, runtime variables are specified using the ampersand (&) character followed by the variable name. For example, to specify a variable named "dept_name", you would use "&dept_name" in the SELECT statement. This allows users to enter a value for the variable at runtime, rather than hard-coding the value into the query.

Option A (percentage sign) is incorrect, as this character is commonly used as a wildcard operator in SQL, but not for specifying runtime variables.

Option B (quotation marks) is also incorrect, as quotation marks are used to delimit string literals in SQL, but not for specifying runtime variables.

Option D (ellipses) is incorrect, as ellipses are not used in SQL syntax for specifying runtime variables.

Therefore, the correct answer is:

The Answer is: C. Ampersand