Let y = f (x) be the particular solution to the differential equation - = y' with the initial condition f (1) = 1. Which of the following gives an expression for f (a ) and its domain? A f (ac) = 2 2: -1 for a # 0 B f (a) = 20-1 for a > 0 C f (20) = , for a # 2 f ( 20) = for a