Jen is interested in examining how having a pet affects sociability among children with Autism Spectrum Disorder (ASD). To collect her data, she sends out an e-mail with a link to an online questionnaire to all parents in Orange County whose children have an ASD. Of these, only 20% of the parents participant in the survey. Why should Jen be concerned with such a low response rate?

a. The small sample size may result in Type I error inflation.
b. Those who did participate are more likely to have bias responses due to social desirability.
c. The results of those who participated may not generalize to all children with ASD.
d. The small sample size increases the likelihood for unreliability of the measure (or instrument).