Chun has created a social media messaging app that is designed to connect parents and children. Parents and children can only message one another, and there are educational games, learning puzzles, and fun videos that can be shared. Most of the content is free, but Chun would like to offer some higher end paid content as well. What must Chun do to make sure the app complies with Federal Trade Commission (FTC) rules regarding unfair practices and purchases by minors?

a. Chun must obtain informed parental consent before allowing children to purchase paid content.

b. Chun is required to provide an optional setting in the app that parents can turn on to prevent unauthorized purchases.

c. Chun must send an email or text message after the purchase is made to parents alerting them of the purchase. Refunds would be determined on a case-by-case basis.

d. Chun is not required to manage the usage of the app's users; that is the parents' responsibility.