The ____ maintains equal pressure on both sides of the ear drum.

Levalbuterol is

a. the same as albuterol. b. the single (R)-isomer of albuterol. c. an equal mixture of (R)-isomers and (S)-isomers. d. the same as racemic epinephrine.

The structure indicated by number 1 in the figure is the ________.

Fill in the blank(s) with the appropriate word(s).