What is the range of frequency that is audible to a human ear ?

Question

$\begin{array}{1 1} (a)\;\text{20 hz - 20 khz} \\ (b)\; \text{30 hz - 20 khz} \\ (c)\; \text{20 hz - 30 khz} \\ (d)\; \text{20 khz - 30 khz} \end{array}$