Answer:
Ellen should visit a friend who has only cats and one who has only parrots.
Step-by-step explanation:
Here is the complete question:.
Ellen noticed that she often sneezes when she visits her friend Robert, who has a cat and a parrot. Ellen wonders if she may have allergies to Robert's pets and decides to conduct a scientific investigation. What should Ellen do next?
A. Ellen should tell Robert that she cannot visit him until he gives away his pets.
B. Ellen should visit Sue who has a horse, a dog, a goldfish, and a hamster.
C. Ellen should call her doctor and insist that she needs shots for allergies.
D. Ellen should visit a friend who has only cats and one who has only parrots.
And the answer is
D. Ellen should visit a friend who has only cats and one who has only parrots.