A 9-year-old child, who was diagnosed with a viral upper respiratory infection 2 weeks ago, returns to the clinic with a complaint of a 2-day history of drooping of one side of her mouth. She is afebrile with a blood pressure of 110/60 mm Hg. Her physical examination reveals an inability to completely close her left eye, inability to wrinkle her forehead, and the drooping of her mouth on the left side. Her smile is asymmetric. The remainder of her examination is otherwise normal. Which of the following is the MOST likely diagnosis? a. Bell's palsy
b. botulism
c. brainstem glioma
d. Guillain–Barré syndrome