Answer
See the explanation
Work Step by Step
The position of the nucleus is the criterion employed in judging whether the nucleus is likely to be radioactive.
Radioactive:
$^{60}_{27}Co$ - odd proton, odd neutron
$^{92}_{41}Nb$ - odd proton, odd neutron
$^{226}Ra$ - high atomic number
Stable:
$^{58}_{26}Fe$ - even proton, even neutron, stable neutron/proton ratio
$^{202}Hg$ - even proton, even neutron, stable neutron/proton ratio
