Eric draws a pattern for art class. He puts 3 squares on the bottom row, 6 squares on the next row, and 12 squares on the third row. If he continues this pattern, which function, f(x), represents the number of squares on row x?
A. f(x) = 3(2)^x
B. f(x) = 3(2)^x - 1
C. f(x) = 3 + 2x
D. f(x) = 3 + 2(x - 1)