Solve the Problem $\mathrm { f } ( \mathrm { x } )$

Solve the problem.
-Let $\mathrm { f } ( \mathrm { x } )$ compute the cost of a rental car after $x$ days of use at $\$ 41$ per day. What is the interpretation of the solution of $f ^ { - 1 } ( x ) = 147$ ?

A) The cost of rental for 41 days
B) The number of days rented for $\$ 147$
C) The number of days rented for $\$ 41$
D) The cost of rental for 147 days