Context Word: feline infectious peritonitis. 
Question: PersonX's thought her kitten had feline infectious peritonitis so she took her to the vet, PersonY. Fortunately, _ was told it was just a kitten cold. 
Answer: PersonX
PersonX's thought her kitten had feline infectious peritonitis so she took her to the vet, PersonY. Fortunately, _ diagnosed it as just a kitten cold.