Planck's constant (h), speed of light in vacuum
and Newton's gravitational constant (G) are three
fundamental constants. Which of the following
combinations of these has the dimension of length?
(1)``\sqrt \frac {hc}{(G)}``
(2) ``\sqrt \frac {Gc}{(h^\frac 32)}``
(3) ``\sqrt \frac {Gh}{(c^\frac 32)}``
(4)``\sqrt \frac {Gh}{(c^\frac 52)}``