Cold Stone Creamery is considering opening a new store in O'Fallon. Before opening, the company wants to know the percentage of households in O'Fallon that regularly visit an ice cream shop. The market researcher contains a list of households in O'Fallon, randomly selects 150, and mails a questionnaire that asks about ice cream eating habits and flavor preferences. Of the 150 questionnaires mailed, 4 are returned. Th survey has bias. Determine the type of bias and suggest a remedy.