Answer
$C. convenience.$
Work Step by Step
$It\:is\:convenience,\:because\:it\:is\:a\:type\:of\:no\:$
$probability\:sampling\:which\:involves\:the\:sample\:$
$being\:drawn\:from\:that\:part\:of\:the\:population\:$
$which\:is\:close\:to\:hand.\:That\:is,\:a\:sample\:is\:$
$selected\:from\:the\:population\:and\:it\:is\:readily\:$
$available\:and\:is\:convenient.$
