Let L(r)be the Amount of Board-Feet of Lumber Produced from a Tree

Let L(r) be the amount of board-feet of lumber produced from a tree of radius r (measured in inches) .What does L(16) mean in practical terms?

A) The amount of board-feet of lumber produced from a tree with a radius of 16 inches.
B) The radius of a tree that will produce 16 board-feet of lumber.
C) The rate of change of the amount of lumber with respect to radius when the radius is 16 inches (in board-feet per inch) .
D) The rate of change of the radius with respect to the amount of lumber produced when the amount is 16 board-feet (in inches per board-foot) .