If f(x)=2xf(x) = 2xf(x)=2x and g(x)=x+3g(x) = x + 3g(x)=x+3, what is the composite function (f∘g)(x)(f \circ g)(x)(f∘g)(x)?
2x+32x + 32x+3
2x+62x + 62x+6
x+6x + 6x+6
2(x+3)2(x+3)2(x+3)