Answer:
A. f: the number of friends attending Alisa's party.
Explanation:
We know that it takes Alisa 10 minutes to full a dozen balloons, and if each of her friends gets one dozen balloons, and if
is the number of friends, then the total dozens of balloons will be
(because each friend gets a dozen balloons.)
Thus we must know
: the number of friends attending Alisa's party, if we are calculate the time Alisa will take to fill all the balloons.