The number of people contacted at each level of a phone tree can be represented by f(x) = 3x, where x represents the level.What is x when f(x) = 27?
A. x = 9; At level 9, 27 people will be contacted.
B. x = 2; At level 2, 27 people will be contacted.
C. x = 24; At level 24, 27 people will be contacted.
D. x = 3; At level 3, 27 people will be contacted.