Let f(x)=x+3f(x) = x + 3f(x)=x+3 and g(x)=2xg(x) = 2xg(x)=2x. What is the range of (f∘g)(f \circ g)(f∘g) if the domain is all real numbers?
[3,∞)[3, \infty)[3,∞)
[0,∞)[0, \infty)[0,∞)
[6,∞)[6, \infty)[6,∞)
All real numbers