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

Ellen should visit a friend who has only cats and one who has only parrots.

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.