Danni$$s Best Scoop $($DBS$),$ a small local ice cream stand at the City A$,$ is very popular and selling a steady amount of $50$ litres of ice cream every day, $360$ days a year. It orders the specialty ice cream directly from Italy. For every order, there is a fixed delivery charge of $30.$ The inventory carrying cost for one litre of ice cream is $2$ per year.

a$)$ Now consider the fact that the available storage space of WBS is only $500$ litres. However, it could rent nearby space for another $500$ litres at a cost of $20/$month$.$ Should it rent the additional space? Explain your reasoning.