Answer: (a)Low

The small signal model of common drain (source follower) circuit is shown.

OUTPUT PART OF COMMON DRAIN CIRCUIT TO CALCULATE OUTPUT IMPEDANCE

Thus, the value of output impedance can be evaluated

$\LARGE R_{out} = {1\over{g_m+{1\over{{r_o}}||{r_c}}}} = {1\over{g_m}}$

The value of $\large g_m$ is made large enough,so the resultant output impedance is low for Source Follower Circuit.