Then Lady grace thought that the only things that Carmina would eat were the aprocot sweet meats that lady Horsely makes. Since the aprocots were yellow and so was the poison.
Lady Grace remembered that lady Horsely lost her son in a duel against Carmina's father. So Lady Horsely would have been angry and sad and would have taken it out on Carmina.
Later on the queen Lady Horsely and Grace took some sweet meats up to Carmina that lady Horsely made. Then Grace asked if Lady Horsely would eat one of her sweet meats, She wouldn't until the queen asked her and she admitted it.