Respuesta :
John sent a valentine to Annabel.
Henry did not send , and Greg would not send . Billy sent one to Mary or Deborah. It remains John
Here the four boys mentioned are Henry, Billy, John and Greg
Henry did not send a card to Annabel
So that leaves us with Billy, John and Greg
Billy had sent a card either to Mary or Deborah, so not to Annabel
This leaves us with John and Greg
Greg would never send a card to Annabel
So this leaves us with John
So John had send a valentine to Annabel