Irrigation expense has a $30$ day, non$$calendar month billing cycle. As of May month end, irrigation expense through $5/30/2018$ has been incurred, however, expense through $3/15/2018$ has been recognized in the General Ledger. How many months of irrigation expense should be accrued to reflect incurred expense through May?

a$5$ monthsb$3$ monthsc$2\mathrm{.}5$ monthsd$2$ months