Which of the following functions is uniformly continuous on (0,∞)(0, \infty)(0,∞)?
f(x)=x2f(x) = x^2f(x)=x2
f(x)=sin(x2)f(x) = \sin(x^2)f(x)=sin(x2)
f(x)=xf(x) = \sqrt{x}f(x)=x
f(x)=1xf(x) = \frac{1}{x}f(x)=x1