If a company decides to stay stay open one hour longer and they project additional gross revenue of $$500$ but also project additional expenses of $$350,$ which of the following is true?

A$.$ Based on the marginal principle they should stay open the additional hour:

B$.$ This is an example of the principle of opportunity cost.

C$.$ This is an example of the spillover principle.

D$.$ They should not stay open the additional hour due to the additional expenses of $$350.$