School administrators conducted a survey to measure parental support of PARCC testing. The survey was mailed to the parents of all of the students in the school, with return envelopes. There were 1,100 surveys mailed out. After one month, 187 completed surveys were returned. Only 53 of those surveyed were supportive of PARCC testing. Which bias is affecting the result? (Selection bias, Response/Measurement bias, or Non-response bias)