What are the domain and range of the function f(x) = 4(RootIndex 3 StartRoot 81 EndRoot) Superscript x?

{x| x is a real number}; {y| y > 0}
{x| x > 4}; {y| y > 0}
{x| x is a real number}; {y| y > 4}
{x| x > 4}; {y| y > 4}