Aditya is assessing the value of IT systems. His company sells sporting goods online. One factor of his evaluation is the required availability of each system. Some systems must be available $24/7,$ while others must be available during regular business hours Monday through Friday. Which of the following would have the highest availability requirements?

Group of answer choices

Server that hosts the customer relationship management application

Server that hosts the accounting application

Email server

E$-$commerce website server