There are several reasons why online courses are increasing in popularity. Which of the following sentences can support this main idea

A、Onlinecoursesareflexibleintermsoftime
B、Onlinecourseshavebeenavailablesincethe1990s
C、Onlinecoursesaremoreconvenientforstudentswholivefarawayfromthecampus
D、Onlinecoursestakemuchtimetomake