Considering the following line in $/$etc$/$shadow$,$ what the number $19376$ represents? rosie:$$6$$NWX$924$YTJObMhm$4$$PX$8/$b$8$uRXTI$416$Q$25$H$76$e$2$p$3$v$5$GXaqwmuU$74$g$241$mKKvzEgpM

a$.$ The number of remaining days to the next mandatory password change

b$.$ The number of days since last password change, starting from epoch date $(1$ January

$1999)$

c$.$ The number of days since last password change, starting from epoch date $(1$ January

$1970)$

d$.$ The number of remaining minutes to the next mandatory password change