John has recently started his own business to sell a new product he has developed. The product is a new design for small, lightweight personal headphones, as would be used with a smartphone, digital tablet, MP3 player or even a radio (they still exist).
John's product will probably be bought by a large percentage of minors by orders taken over his internet site.
(a.) Advise John as to any defense(s) that a minor (someone under 18) may have regarding a purchase. Please explain in detail what defense(s) may apply and what might occur.