A manager wants to build $3$ control limits for a process. The target value for the mean of the process is $10$ units, and the standard deviation of the process is $6.$ If samples of size $9$ are to be taken, the UCL and LCL will be

a$.-8$ and $28$

b$.16$ and $4$

c$.12$ and $8$

d$.4$ and $16$

e$.8$ and $12$