If f(x)=x+4f(x) = x + 4f(x)=x+4, what is the expression for f(f(x))f(f(x))f(f(x))?
x+8x + 8x+8
x2+8x^2 + 8x2+8
2x+82x + 82x+8
x+4x + 4x+4