Which frequencies does Zigbee operate on$?$

$2\mathrm{.}4$ GHz$,900MHz,$ and $868MHz$

$2\mathrm{.}7$ GHz$,400MHz,$ and $865MHz$

$2\mathrm{.}4$ GHz$,500MHz,$ and $818MHz$

$1\mathrm{.}4GHz,90MHz,$ and $500MHz$