After completing a time study with $5$ observations, you have times of $4\mathrm{.}71$min,$5\mathrm{.}25$min,$4\mathrm{.}98$min,$4\mathrm{.}62$min, and $5\mathrm{.}01$min for an average time of $4\mathrm{.}91$min. The worker is rated at $105\%.$ Which is a reasonable standard time for this process?

a$.4\mathrm{.}95$min,$5\mathrm{.}51$min,$5\mathrm{.}23$min,$4\mathrm{.}85$min,$5\mathrm{.}26$min

b$.5\mathrm{.}16$min

c$.5\mathrm{.}78$min

d$.5\mathrm{.}69$min,$6\mathrm{.}34$min,$6\mathrm{.}01$min,$5\mathrm{.}58$min,$6\mathrm{.}05$min