Answer: The reliability she should demonstrate is the test-retest reliability. Because it will help her to determine the accuracy of the answers parents provided in the survey.
Explanation: Test-retest reliability is the a type of reliability that is used to determine the accuracy of a score. This is done by given a question to students to answer, and given them the same question again after a period of time.
For Rancesca to determine the reliability of her result from a survey questions, she should give the same survey questions to the same group of people to answer again, after a period of time.
This will help her know if what each parents has answered according to their Behavior. Because a parents that answers according it's behaviour is likely to provide the same answer.