The average zinc concentration recovered from a sample of measurements taken in $36$ different locations in a river is found to be $2\mathrm{.}6$ grams per mililiter. Assume that the population standard deviation is $0\mathrm{.}3$ gram per mililiter. Which one of thr following defines a $95\%$ confidence interval for the mean zinc concentration in the river?

A$)(2\mathrm{.}47$;$2\mathrm{.}73)$

B$)(2\mathrm{.}50$;$2\mathrm{.}70)$

C$)(2\mathrm{.}52$;$2\mathrm{.}68)$

D$)(2\mathrm{.}55$;$2\mathrm{.}65)$

E$)(2\mathrm{.}48$;$2\mathrm{.}72)$