Answer
$c. Stratified$
Work Step by Step
$It\:is\:stratified\:sampling,\:since\:a\:stratified\:$
$sample\:is\:a\:sample\:obtained\:by\:dividing\:$
$the\:population\:into\:subgroups,\:called\:strata,\:$
$according\:to\:various\:homogeneous\:characteristics\:$
$and\:then\:selecting\:members\:from\:each\:stratum\:$
$for\:the\:sample.$
