An organization that tries to get the best possible estimates before responding to RFP$$s$.$ Assuming that the ends of a range of estimates are $+/3$ sigma from the mean, which of the following range estimates involves the least risk?

A$.30$ days, plus or minus $5$ days

B$.22$ to $30$ days

C$.$ Optimistic $=26$ days, most likely $=30$ days, pessimistic $=33$ days

D$.$ Mean of $28$ days